Somewhere towards the top of the list of cars that are not well suited to rallying - a little way short of the Renault Grand Scenic but some way clear of the Audi A6 - you will find the Jaguar F-Type Convertible. A belly-scraping two-seat sports car with no roof and one driven axle clearly has no business whatsoever being out on a rally stage, kicking up dust and spraying gravel at fir trees. Watching this F-type slither around Walter's Arena in South Wales is odd, like seeing a cat playing fetch.

We all know very well that a rally car has a roof and four-wheel drive, and that far from being based upon a rakish two-door roadster that you or I might quite like to drive they are actually derived from little hatchbacks, the sort you would buy for your first-born. At least, that is what rallying seems to have become. Many decades ago, when the sport was less about flat-out 15-minute dashes through a misty forest and more a test of consistency and regularity over enormous distances, the cars took near enough whatever form the competitors of the day cared to imagine. Rallying back then was a sport contested by tiny little sports cars and big saloons, by hefty luxury coupes and French oddities on hydropneumatic suspension. It was the most inclusive form of motorsport going.

That's why there was nothing at all unusual about a particularly adventurous young couple turning up to compete on the era's most famous rallies in a belly-scraping sports car with no roof. Ian Appleyard and his co-driver and wife Pat - who probably had a useful degree of influence within the Jaguar Cars firmament by dint of being Sir William Lyons' daughter - didn't merely turn up to those rallies; they won them. Aboard their pretty little off-white XK120 - registration plate NUB 120 - the Appleyards won Britain's RAC Rally in 1951 and scooped the very highly prized Gold Cup on the once very prestigious Alpine Rally in the early Fifties.

Nope, nor did I. Jaguar's rallying heritage is a very well-kept secret (unlike its, erm, unfortunate history with Formula 1). 2018 is the year the pioneering XK120 celebrates its 70th anniversary and to mark the occasion, Jaguar wanted to do something fun. But it had to be something a little off-the-wall...

So how exactly do you go about turning a convertible F-type into the sort of car that can be hammered across a bumpy gravel track at three-figure speeds without rattling itself to pieces? First of all you approach your in-house special projects department - that'll be Special Vehicle Operations in this case - and then you enlist the expertise of a very well-known British rallying specialist. This car has been built in accordance with the FIA's very strict regulations, but it isn't actually homologated because the sheer cost and weight of paperwork necessary to do so would be enough to put anybody off.

So much underbody protection has been fitted you could use the car to clear a minefield - probably in record time - while the folding hood is ripped out altogether, replaced by a chunky roll cage. The wheels are 16-inch items wrapped in knobbly gravel tyres and although the suspension arms are carried over from the road car, the springs and dampers are proper motorsport items (the latter supplied by rally gurus Exe-TC). Prepared for gravel, the car rides 40mm higher than a road-going F-type.

It has all the usual refinements that mark out a rally car, too, such as competition seats and harnesses, uprated brakes, an intercom, a lamp pod, an extinguisher and even an oversteer lever (referred to in some circles as a 'hydraulic handbrake'). Jaguar might have taken the more obvious route and based its rally car on a four-wheel drive F-type, yet it chose the rear-driven 300hp four-cylinder model instead, partly because it would be more slip-slidey fun, but also because it's the most recent model. The LSD from the V6 model has been fitted in place of the standard open differential, while every one of the showroom car's electronic driver aids has been disabled. It uses the paddle-shift auto 'box rather than the six-speed manual, which means this rally car has no fewer than eight forward gears.

And so it is that Jaguar rolls back the years and makes its triumphant return to the sport it once excelled at. Well, not quite. No homologation papers means no competition. This F-type will never actually take part in a rally. We might see it in action as a course car, but it'll never go up against the stopwatch. So it's a mock-up. It's role-play. It's like one of those guys who wears a captain's hat at home to play a flight simulator. It isn't actually a rally car. But I bet you still want to know what it's like.

Until I've driven the car myself there is only so much I can tell you, although I have sat in the silly seat for a handful of laps of Walter's Arena alongside young rally driver, Jade Paveley. I tried to remember to sit on my hands just in case...well, it's hardly worth saying why. Once you've grown accustomed the curious sensation of the wind swirling around the cabin and dust slapping you in the face at every turn you begin to realise how well the car works across the sometimes very rough terrain.

Those Exe-TC dampers are so effective I want to know why they aren't fitted to every road car (oh yeah, they cost a fortune) and from the co-driver's seat you feel as though the car is resting on a pocket of compressed air, never scraping its underside across the gravel track and always feeling beautifully controlled. If you ever want to know exactly what dampers are actually for, you should simply ride in a rally car across a rutted forest stage. What the F-type doesn't have is a foot and a half of suspension travel, so when Jade spots a deep ridge perpendicular to the road - the type that's formed over time by runnels of water and that the crew of a modern World Rally Car would skim over without even noticing - she has to slow the car down quite significantly to avoid bending the bodyshell in half. Everywhere else, though, the suspension is like witchcraft.

I will always be amazed by how much mechanical grip a gravel tyre can find on a loose surface and in the Jaguar I was as surprised as I've ever been. I reckoned it would be an oversteer machine, wanting to swap ends at the merest hint of a throttle application. But from where I was sitting it felt as though it took the full Juha just to make the car slide a little. It had bundles of turn-in grip, too, and it hauled itself down really hard when Jade stood on the brakes.

The thing about top-flight rallying in its current form is that if you want to win, you need to start with a small hatchback. That's the real reason Jaguar won't field this car in competition; it'd get murdered by an i20. Cars like this F-type and the completely brilliant 911 GT3 that the equally brilliant Richard Tuthill built out of a Porsche Cup car do make me stop and wonder if rallying might be more fun for everybody if we ditched the Fiestas and C3s and switched to rear-wheel drive sports cars instead (roof optional).