“Mind you,” adds Bob as he checks panel fastenings, “the drivers said the 25 was better on corners but the 24 was more forgiving.” DC strides past to change into sponsor’s overalls for another task and pauses to introduce himself to me, not the other way around. “Let’s talk after the drive.”

There are earlier contenders for the first racing monocoque, but this is the car that in one unveiling moment sent every other designer to his drawing board, and Colin Chapman to the front row of the design grid. No, it didn’t win first time out, and spaceframe BRMs, Coopers and Porsches still scored victories in 1962, but this was a balance-tipper: if you didn’t follow you were going to be left in the wilderness. By 1964, four of the six constructors would be running monocoques.

“Everyone at Lotus knew about the secret car,” recalls Cedric, “but there were no leaks. We took it straight to Zandvoort in 1962 without even a test run. And Dan Gurney said, ‘With a car like this we could win Indy’.” Among the dunes Jim’s clutch failed and Trevor Taylor’s 24 followed Hill’s BRM to the flag, but in the revolutionary machine Clark would score another three championship wins at Spa, Aintree and Watkins Glen, almost enough for the title as he led at East London in South Africa — until the oil escaped from the Climax and a season-long tussle fell to Graham Hill. For 1963 there would be no doubt at all. On smaller, fatter 13in wheels and with improved suspension geometry, this slim panatella of a car would in the shy Scotsman’s hands reel in pole after pole, seven grand prix wins and five non-title victories and make Clark champion for the first time. The greatest driver of the era (pace the injured Moss) had squeezed into the cleverest car and no one could stay with them.

Coulthard is back for a seat fitting, now in white overalls once more. It’s hard work, being famous. Abandoning the seat padding he wriggles down between those tanks, asking Bob if this is how Clark sat, click-clacks the gear lever, practises heel and toe. “Have to think myself back to the 1980s,” he grins, arms and broad shoulders spilling over the car until Bob and Derek cap him off with the bodywork. Everyone decides this will work, the body comes off and he clambers out. “I can almost get my hands on the ground!” he exclaims, used to being ears-deep in carbon fibre. He has questions: he’s been reading up about the 25, asks about fuel capacities, seat position, whether drivers complained about heat from the front radiator. He’s never sat behind one in a racing car — a hotshoe who’s never had hot shoes. “They just put up with it,” shrugs Bob. Film crew collars him again; Bob removes the hair drier, climbs in (pretty spry for 77), flicks on pumps, checks for neutral, hits the starter. Everyone except Bob jumps as the V8 bark echoes round the pit. DC looks over and smiles.

While the Climax warms, Cedric has produced a photo album and the Lotus boys, plus team photographer Peter Darley, still snapping 50 years later, trade stories about all-nighters, relentless lorry drives to Italy, practical jokes shared with the Grand Prix stars in their hotels. The thread to the current Lotus F1 race team may be long since broken, but if Team spirit continues it’s among the lads who are still part of CTL.

Ten minutes later the temperatures are up. Bob cuts the engine, the car is pushed to the pit door and DC gets out goggles and helmet — not the one we know, but an open-facer painted with the Scottish saltire especially for today. “I couldn’t drive Jim’s car in a full-face job,” he smiles. Belt buckles lock him down and he looks up at Dance. Suddenly a man you’d pass in a crowd and a man who creates a crowd have swapped authority: Coulthard is the tyro, Dance the expert in charge. He’s strapped in a hundred drivers before; this is just another grand prix winner. He nods, the V8 barks and DC propels the green and yellow machine smoothly down the pitlane.

A gentle lap, a firmer one, then open throttles as he explores how a car moves on tyres with large slip angles, how it dances on those soft springs. When he returns for a check there’s a big crowd — finally word has got around. Helmet off, he lets every lens catch his smile, ever the professional, before Bob checks everything and he goes out again, some laps for the Beeb, some for our photographer, some for himself.

“That was brilliant! Really cool! Never thought I’d be so excited. I feel completely at home. For a moment I almost felt like Jim Clark — then I woke up.” The car is back, engine ticking as it cools, shutters clicking as DC extricates his lengthy frame, pulls off the crash hat, tidies his hair in the mirror. “Got another wig somewhere. Oh no, it’s Eddie’s.” All laugh, and the public performance is over; the roller shutter lowers and car and star are secluded inside for our debrief and photo shoot. Photographer Matt Howell wants to catch DC inspecting the Lotus; that’s no effort as he’s already asking Cedric and Bob about damper placement, sliding-spline driveshafts, the ducted air screen. Maybe it’s for his BBC piece, but then he gets out his phone and takes his own pictures. Later I ask Cedric if Clark was au fait mechanically. “I wouldn’t say he had trouble holding a screwdriver, but…”

The BBC steals David back, an unspoken tug of war between us. The cameras are insatiable; a tense director orders DC to walk around the car looking pensive, then the other way, to redo his lines describing that first-lap moment at soaking Spa in ’63 when Jim Clark surged from eighth to first to eternal legend, first victory for the 25 that steam-roller season. DC is patient until he makes the same fluff four times and bad words erupt. Maybe he prefers working live, quizzing his peers on the grid, no lines to learn.

My turn again, asking about sitting in such a slim car. “You have great visibility but I did feel exposed,” DC says. “You feel that at Monaco you could almost reach out and touch the barriers. I was very aware of the tanks wrapped around me, and the hot air blowing up from the cooling system.”

“Everything was packed tight inside,” adds Cedric. “With the 11/2-litre engine Colin wanted the smallest frontal area so everything came inboard, including the dampers.”

“Now I see how drivers from that period drove with straight arms,” DC continues. “There’s not a lot of load in the steering. A huge amount of lock, but not much load. In a modern GP car there’s so much load and feedback it self-centres; this doesn’t, or at least not with the same force, so you have to centre it yourself and be delicate. Hence the straight arms. Made me feel like a real racing driver. Haven’t felt like that before…”

A bit of a squeeze, though? “It was, like the Leyton House I drove for you guys last year — ridiculously small cockpit but once you’re doing your thing you don’t think about it. It was difficult for me to get to fifth — I had to do a reverse-hand upshift. That would have cost me time in a race.”

“The Old Man used to say ‘there’s no substitute for wheel movement’”

Did he reach for a shift paddle? “Ha, ha! Not once. Thankfully I’m long enough out of F1 that that’s no longer my default setting. But the first F1 car I drove, the McLaren in ’91, had a manual shift anyway. That V8 — it’s not a young engine, but it’s smooth and it delivers. They said I could go to 9000 — I only went to 8.5 but that was useable rpm. For the grip it had it could handle more power; that’s just under 200 and it would comfortably handle 50 more. But that’s what they had at the time.”

So he didn’t get it sliding… “Nope. Generally it pushes a little at the front. I almost had it drifting at Stowe where it’s fast, but I didn’t want to find out I’d got that wrong! I’m used to downforce pushing the car into the ground, but without that it moves around so much more. You can feel air under the car. Presumably it generates lift at speed?” he asks Bob.

“If you go fast enough.”

“The idea of the high ride level was to get the air passing underneath,” explains Cedric.

“And it’s softly sprung,” adds Bob. “The Old Man used to say ‘there’s no substitute for wheel movement’.”

“It certainly moved laterally in a straight line, more affected by the wind than I expected, almost as if it’s floating on a current of air. It made me feel a bit uncomfortable in Turn 2, the long, fast left-hander. I’m sure in a classic expert’s hands it would be flat, but I didn’t want a high-speed rotation. But you’d get used to it; that would be your reality. In the low-speed corners I was starting to play a little with the brakes and the downshift, feeling really pleased to be behind the wheel.

So it was a pleasure?

“Yes — it’s a racing car! Any road car on the track, even the DTMs I’ve been racing, is still a compromise. This is designed from the start as a racing car, designed to win Grands Prix. There may be less road feedback, but it delivers both lowand high-speed grip in proportion. A modern GP car develops grip in an out-of-proportion way — at low speed there is relatively little because there’s no downforce, but at high speed the level of grip is difficult to comprehend. So a normal person jumping into this could quickly get the feeling of the low-speed, medium and high-speed grip. It would still take one of the greats like Jim Clark to balance the lateral forces against the extremes of tyre adhesion, though.”

I’m conscious he has a plane to catch, but as we talk he never looks at the enormous watch under the sleeve of his tailored blue shirt, his fourth clothes change so far.

“What stands out here,” he resumes, “is the drivability of that little V8. A modern F1 engine is peaky — you have to rev it constantly and it’s annoying. This has only five speeds but you get a journey through the gears that is 100 per cent more pleasurable. You feel the dog going in and you think ‘I’ve just rounded the corners of the dog a little bit and I’ve got two hours to go…’ I know when Jim won here it was 2hrs 14min, where most of my races were 90 minutes.”

Clearly he’s been doing his research. “I wanted to learn the 25 story because I didn’t know it in detail. My racing history is pretty good from the ’70s on when I was watching with my dad, who was a fan of Jim and got his autograph. But I don’t have anything from that period in my own museum, not like Dario [Franchitti]. I rang him to boast about this because he’s a big, big Clark fan. But the legend is there for good reason. It was a remarkable period in the development of motor sport; the genius of Colin Chapman and the great driving qualities of Clark.”

What about some historic racing?

“I’m proud to have done it” David Coulthard

“This was brilliant, but with my lifestyle, all the GPs, not seeing enough of the family, I’m not tempted. But beyond my current career? Why not? I’m a racer. We’re sitting at a track and it may be in the nice comfortable Silverstone Wing, but if it we were sitting on plastic chairs at the side of the track we’d still feel comfortable because racing people go to racetracks. I’ve been going since I was a kid and I hope to be doing it as an old man.”

DC and JC both took the chequered flag here. Did he feel the connection?

“Very much. I actually whooped on Hangar Straight! I’ve never done that before in a car. It’s just how I felt. Pleased and honoured, connected with a piece of history that guided the path of Jim Clark and many British drivers. I’m proud to have done it.”

It’s airport time. DC punctiliously shakes hands with everyone and strides off towards Spain. Bob and Greg the driver strap down a priceless element of British racing history in the lorry and head for Norfolk, three hours away. Getting up at 5am is nothing new for the Lotus lads — even if they’ve been doing it for six decades.