cover of Motor, 1967, July 19

The Imp Site

Probe 15 : design or doodle

by Roger Bell

week ending July 19 1969


Does it work ?

When it was first seen at the Racing Car Show, no one believed that it actually worked. Surely, it was just a modern objet d'art, a fancy doodle in glass fibre, an exercise in imaginative exotica. Clever, striking, rather fun... but surely not real. Probe 15 squatted on the Marcos stand, but is was really just a guest there, since the Adams brothers who designed and built it, no longer have any formal ties with their Marcos neighbours at Bradford-on-Avon.
A fible glass body, styled by Dennis Adams, clothes the marine-ply monocoque shell. As in the helicopter behind, you are exposed to full view, like a goldfish in a bowl, behind acres of glass and plastic screen. Ten-inch front wheels keep the bonnet line spectacularly low; 13-inch ones at the back are driven by a Hillman Imp engine in the tail. Odd wheels mean two spares which virtually fill the slender front boot.
Even so, the Probe and the Marcos have an inseperable ancestry despite the autonomy of the parent companies now. As everyone knows (don't they ?) the striking body of the Marcos 1600, latterly the 3-litre, was the handiwork of the Adams brothers. They were also deeply involved with development of the unique marine-ply monocoque chassis.

So it is hardly surprising that probe 15 (Adams' 15th design exercise) is in style and concept somewhat Marcosite, if a lot more way out.


We were never really convinced that the car did work, until our friends at Hexagon Motors in Highgate called to ask if we'd like to drive it. Such was the impact of this striking projectile on the pop world, with whom Hexagon do brisk business selling high-class E-types, Marcos and other extravagant machinery, that they secured the sole rights to market the car -or at least something like it, to be known as Probe 16, for which a limited production run was planned.
Well, Probe 15 does work - surprisingly well in some ways - and we present here a sort of pictorial road test.

But what of the Adams brothers themselves? What do they do? Why did they make the probe? What have they got up their sleeves? read on...

Wrought Iron

We picked up the trail somewhere in the middle, along with a coach load of day trippers, at The Forge, Bradford-on-Avon, where Mr. Adams senior was delicately welding the final whirly-curls on to a wrought iron well head. Down below, the forge, gnarled and discoloured with age and heat; up above, a white-washed display loft, held together by sagging timbers. Gates, candlesticks, fire grates, vase holders, abstract shapes lay around in neat disorder. The day trippers examined their pocket money...

Dennis and Peter Adams, in their late and early thirties respectively, bought the old blacksmith's shop, lock, stock and rubble, a few years back on the understanding that it was left just as it was. 'Upstairs there was about three feet of dust, which should have been full of vintage goodies; we ploughed through, but there was nothing there.'
At first they regarded the place merely as makeshift headquarters for the design and studio work on their first love - motor cars. 'But people kept coming to get their gates and fancy Martini garden furniture done', recalled Dennis Adams, 'so we went into the wrought iron business'. That the Adamses turned a dying art into a thriving concern, without knowing the first thing about wrought iron reflects their flair for design and creation which started many years before with home-made specials.


If you like crowds, buy a Probe. People gather round whenever, wherever you stop. With mini-skirted passengers, this can be fun, since the only way out is through the sliding roof (left) which can be left open on the move for ventilation -and needs to be on a hot day to combat the greenhouse effect inside.

Building a car

Teenage enthusiasm in those early days was not matched by dramatic success and they quickly discovered that to build a respectable car, you'd got to know more than a little about suspension and chasis design. Peter, the constructor and developer of the partnership, learnt the basics of it through formal academic channels; Dennis, artist, inventor and and visionary, learnt the hard way, much of it with Brian Lister during the Lister-Jaguar heyday.
It was here he first met Frank Costin, one half of another pair of talented brothers, when Costin was brought in to design a new competition car. Unfortunately, family pressure and Archie Scott-Brown's death brought the Lister venture to a premature death, but the Adams/Costin association was renewed shortly after in North Wales when they started work on the original cycle-winged Marcos for Jem Marsh in an old coach house at the back of a hotel garage.


Costin and Adams worked well together, but didn't see eye-to-eye on styling. As Dennis explains: 'I wanted the cars to look prettier and prettier and Frank wanted them to be more and more functional, which were divergent courses'. There was an impasse and the team split up.

The Adamses planned a return to Cambridge to set up on their own, but then Marsh offered them the design and styling work on a new Marcos. So they moved to premises in Luton, which, if a little nearer industrial civilization, were little better than the ones they had just vacated in North Wales.
'We worked in an old hat factory in Jubilee street, which had a hole in the front wall which used to be a front door, and cobbles that went around the back... the upstairs bedrooms we knocked together to do the glass fibre work in. It was another gull-wing car, but I had done all the outside styling and Peter had done the chasis, which was slightly different from the old Costin one. They turned out to be quite popular, as the Costin car had been...'

While the Monocoque Body and Chasis Co. (nicknamed the All-to-cock, Shoddy and Bashy Co.) that then produced the Marcos held its own, an associate concern, Speedex, didn't and eventually the whole Luton venture came to a standstill.
This time the Adamses did return to Cambridge, in 1961, where they started work on their own way-out mid-engined three-seater with sliding doors, a Perspex bubble top and a central driving position. 'It had an aerofoil over the top and a spoiler at the back long before anyone else'.


They worked on this project, known as XP, for six months, during which they were under continuous pressure to return to Marcos.
'When Greville Cavendish -a damned fine chap- turned up, we decided to go. The plan was that Jem Marsh should manage, and we design and develop, the XP; that was the car that Marcos were going to put into production.' For a time the outfit operated from yet more makeshift premises -a workshop next door to Paddy Gaston's in Kingston. 'Eventually we found these old mills in Bradford-on-Avon, next to a big weir on the river, which we immediately fell in love with.'

    Drivers seat
The cockpit, a combination of Formula 1 and science fiction, is surprisingly comfortable, despite the joggly ride, once you have become accustomed to lying on your back with your legs straddling the steering wheel support. Instrumentation is minimal, the view forward and sideways superb (but terrible aft, unless the roof is shut), and the switchgear handily placed on the right.

Fancy king posts

As a production stop-gap, all outstanding stock of the old Luton Marcos was brought up to run the company on. They made an open car (based on a closed one that Peter had converted earlier) and then a removable hardtop for it, that looked like a Ferarri-bred van. Meanwhile, work continued on XP.
'What we had completed for ourselves at our own expenses would have been a little less sophisticated than Marcos and Cavendish could afford. So we decided to make it a little more like a Porsche in spec and design. Your legs went between the front wheels, so that the front suspension and steering had got to be out of the way. This meant fancy king posts with steering arms that stuck up in the air to get the rack over your legs. This hadn't been done before. It was ony later that people started building GP and GT cars with this particular design...'


But changing the spec meant extending the development programme and sales of the ex-Luton car were running dry. They needed something else, quickly, to sell. Dennis Adams takes up the story: '...I said I'd do a quick stop-gap on the Luton chassis, just another body, just to give the car another bit of a boost. So I whipped one up - and they're still selling it.'

Thus does Adams dismiss the briljant design which established himself as a designer of force and originality and Marcos as a specialist constructor of real distinction.
The subsequent success and development of the Marcos 1800, elevated now to the formidable 3-litre, is another story.

Ironically, for Dennis Adams it meant a temporary halt in production-car design. With the fantastic demand for the rebodied Marcos overwhelming the works, interest in the XP project inevitably waned. Instead, a development section was formed to take in design work for outside people - boats, a church steeple, grain hoppers, furniture, toys, a bobsleigh, a commuter car that stood on its tail.
All were invaluable fodder for Adams' imaginative pen. But they were a bit divorced from cars. So, once again, the brothers left Marcos, to set up on their own. They've been self-employed ever since. It was at this time that they went into the wrought iron business, just down the road from Marcos and, quite by accident, next door to Jem Marsh's father, who ran an antique shop.

Car designs in commision

The Adamses were commissioned to do various car designs before and after their final break with Marcos: a three-wheeler city car; a 200 m.p.h. racer for which John Tojeiro had done the basic GA's; a one-off 2+2 body shell, Marcosite in appearance, for a brand new Bentley chassis; GT body shells for a South African manufacturer to wed to BMC 1100 platforms.


It was actually after the Adamses had left Marcos that they did the Mantis for Jem Marsh, the original design for which -as photos of the model show- was uncannily like Bertone's Carabo that came two years later. So much of the car was changed during development, though, including the engine (several times) and the wheels, that the final shape was nothing like the original. 'Everybody thought it looked exciting because it was so vicious, so brutally ugly. But we weren't too happy with it.'

Probe 15

After a 7-litre sports car design for an American, work started on their 15th car, which they subsequently called Probe 15.

'This was something we'd always wanted to do -a car free from all the rules and regulation. If it was physically possible to drive a car lying flat on your back and looking through your toes, we'd do it. It was just an exercise to go really extreme; it was just for us, like the XP had been.'

    pop-up light
Electric motors pop up the head- lights.

As seen from the front
Probe 15 has a flat screen swept by a single double-bladed wiper: Probe 16 will have a more conventional curved screen.

Probe 15 wasn't planned for publicity (something the brothers have never actively chased) or as a commercial proposition, but it aroused such universal interest at the Racing Car Show -the Board of Trade subsequently sent them newspaper cuttings from dailies throughout the world- that they were forced to re-examine its role. They had scores of offers for the Show car (which was eventually sold to a South African through Hexagon Motors) and a request to supply bodies to fit to VW platforms. They even had negotiations with an industrialist to manufacture the car as it stood.
In the end they decided to build it themselves.

Probe 16

Adams freely admits that several modifications were needed. 'Probe 15 was underpowered; it had a pretty good top speed (over 100 m.p.h.), but it just wasn't dynamic enough. The cockpit was too small and we knew we'd have to go back to the old XP-type sliding door.' In 16, the roof and sides, down to elbow level, slide back under electric power from the curved windscreen, when you insert the ignition key into a wing lock. You then ease the seat back into an upright position on its ball bearing runners, step over the sill on to the floor, sit down and slide forward again into a prone position. A press button shuts the roof -and there is a manual over-ride if the electrics fail. All very ingenious; and all in the interest of ultra lowness.

We saw the first Probe 16 under construction, not in The Forge, where 15 was evolved, but just down the road in a slightly larger timber loft -the last makeshift premises, it is hoped, before permanent headquarters are found in which to establish the Adams as autombile manufacturers. The car hasn't changed much in appearance (though the curved screen makes it look even sleeker), but in detail there are a lot of alterations. A cross-wise BMC 1800 engine and suspension ('we didn't want to use the fancy gearbox') drives Imp-suspended rear wheels of enormous width which, like those on the 15, are bigger than the front ones. Only with tiddlers on the front could the profile be kept as low as they want.


'All cars should have different sized wheels', says Dennis Adams, slightly tongue in cheek. 'Old Daimler realised that in 1895. If a chap from another planet settled down here to design a motor car without ever having seen one, he'd automatically make it with big, powerful rear wheels for colossal leverage and great urge to throw the car forwards, and small wheels on the front to steer with. All you've got to do is ensure that there is enough rubber on the road up front for breaking -which is why we've got these bloody great fat Goodyears; marvelous tyres. But in any case, with the mass weight of the car on the back, you don't rely much on weight transferance for braking. More braking on the back is a hell of a lot more stable than the wavy, wobbly braking you get on competition cars going into corners fast where the front wheels are doing the lot.'

The spare problem will be resolved simply by providing one (small) front wheel, which will temporarily, if rather lop-sidedly, support the back if needs be.

We asked about the effect of extreme styling on the car's handling (recalling that Probe 15 actually handles very well) and that an ultra low car runs into ground clearance problems on anything higher than a white line. Adams' answer reflects his original approach to such problems.

Ground clearance

'If you make a pencil thin silhouette and wrap it round a bloke in a reclined position, you can stick a bloody great box underneath for his bottom and no one will notice. Actually, we decided to make cars with plenty of ground clearance (about six inches).

High roll centre

'If you wanted absolute stability in the early days, well before suspensions were properly sorted out, you got everything a low as posible. But if the suspension geometry was wrong, half the effort was wasted and the car still didn't handle on corners. So I then started to think about getting roll centres higher and higher and the combined roll axis high right throughout the car.
This was at a time when people were still reluctant to build cars with no-roll fell. Costin was convinced that a car had to roll a little to give a chap 'feel' on corners; I was convinced that it hadn't. If anything, it should pendulum the other way. So the Marcos 1800 was the first car we made with absolutely no roll; the roll centre was so high, that the car just shoved you sideways on corners. Such a design allows you to put the heavy gubbins -the engine, running gear, petrol tank and so on- relatively high to get a decent ground clearance. So every car since the Marcos has got this very high roll centre.
Getting everything as low as possible is only necessary if you are doing a screaming-limit competition car, to get every microscopic ounce of benefit from the design. But with a road car it isn't essential.

Weight distribution

'Probe 15 weighed 11¼ cwt, eight on the back, about three on the front. Now that seems a terrible weight distribution, but we didn't worry about it. If you've got on the front proportionately the same sprung to unsprung ration as on the back, then you have your handling back again. Because of a physically greater mass on the back, that's trying to throw itself out centrifugally on corners, and because the front is so light, one automatically thinks that you've got a fantastically oversteering car, that's going to spin on the first corner. So the first thing you think of is to put the battery, spare wheel, fuel tank and so on in the front to even up the weight distribution. Forget it. Put tiny wheels on the front instead to induce greater slip angles, and the monster ones on the back to cut them down, and you've got a normal motor car again.'

Probe 15 had independent Imp swing axles at the front, but 16, in keeping with its styling, goes wayout with a light, rigid beam axle following, if not quite pioneering, a trend that Chapman and others have been investigating for some time. Eventually, the Imp rear end will give way to their own De Dion arrangement, and there's a 4.7-litre V8 -Probe 17- with America in mind.

One thing the Adams are not short of is ideas.


Sent to me by Nic Rowley; photos scanned by Martin Davies.
"Remember I spoke (emailed) you some time ago
about the probe and I thought your history was wrong ?"

Earlier exercises from the Adams brothers - the gull-winged Marcos (1959).
The 3-seater mid-engined XP of 1962. In modified form, XP was to have gone into production as a Marcos. Marcos 1800
The classic Marcos 1800, latterly the 1600 and 3-litre, is Dennis Adams' best-known design. Marcos Mantis
Marcos Mantis GT body shell
GT body (as a model) to be mounted on a BMC 1100 platform.
    Trying to follow the count
  1. Dennis Adams learned much of the basics of suspension and chasis design with Brian Lister.
    Shortly after Adams/Costin started work on the original cycle-winged Marcos for Jem Marsh
  2. a closed one
  3. Marsh offered the Adamses the design and styling work on a new Marcos, another gull-wing car. Marcos Gullwing, 1962
  4. In 1961 they started their own mid-engined three-seater with sliding doors, a Perspex bubble top and a central driving position, an aerofoil over the top and a spoiler at the back: XP, 1963
  5. production stop-gap: an open car (based on a closed one that Peter had converted earlier) and a removable hardtop for it, that looked like a Ferarri-bred van.
  6. another stop-gap on the Luton chassis, 'just another body', the 1964 Marcos 1800 using the Volvo B-18 engine
  7. design work for outside people - a.o.: a commuter car that stood on its tail
  8. in commission: a three-wheeler city car
  9. in commission: a 200 m.p.h. racer for which John Tojeiro had done the basic GA's
  10. in commission: a one-off 2+2 body shell, Marcosite in appearance, for a brand new Bentley chassis
  11. in commission: GT body shells for a South African manufacturer to wed to BMC 1100 platforms
  12. in commission: GT body shells for a South African manufacturer to wed to BMC 1100 platforms
  13. the Mantis for Jem Marsh, so vicious, so brutally ugly
  14. a 7-litre sports car design for an American
  15. Probe 15, 1968


Adams Probe Motor Co.
Concept Centaur
The Imp Specials
The Imp Site

Roger Bell

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ISBN: 1899870202 (Hardcover)

Haynes Book of Modern Sports Cars / Roger Bell. - Haynes, 2000. - 192 pages
ISBN: 1859606768 (Hardcover)

Antique racers for antique dealers : old racing Volvos : Roger Bell says tanks for the memory. - Car Magazine, issue 421, september 1997. - p. 125

Roger Bell in Car, September 1997 on a test in a Group A 240 Turbo: "I've driven some mad machinery but nothing with such an excess of grunt over grip as this"

Production Car Racing 1973/ 74 / 75- Avon Motor Tour of Britain - 3 days of circuit racing and rallying in road cars-great stuff ! Roger Clarke, Gerry Marshall, Tony Pond, James Hunt, Noel Edmonds, Roger Bell, Jody Scheckter, etc..featuring Capri mk1 & Escort mk1, Camaro, Firenza, Avenger GT, Dolomite Sprint and more....
13- 60min