I’d like to think I’m a fairly responsible and trustworthy sort of bloke. Certainly, when they write the history book on the Jaguar XJR, I’d like to go down with the honour of being the first man from outside Jaguar to have ever driven the latest edition of the big V8 super-saloon, and not have that fact supplemented by also being known as the man who stacked it on the first corner at the Goodwood Festival of Speed hillclimb within 10 seconds of it making its global dynamic debut.

Read a full review of the Jaguar XJR here.

So after Jaguar chassis ace Jeff Mitchell has given me the most thorough of briefings on the new 542bhp 5.0-litre supercharged XJR and I’ve learned from the man who helped develop it just how capable it is, I promise myself as much as Jeff that I’ll take good care. 

One straight and one corner later, it’s quite clear that the XJR is going to be every bit as epic as Jeff said it would be. This is a car that, on first acquaintance, can do things that bely its five-metre-plus length and almost two-tonne kerb weight. It’s a good job I gave it that extra bit of care and respect as although it’s a looker, it doesn't scream 542bhp and supercar-baiting performance. 

It does indeed have those things, though. And it is fiercely quick in a straight line with it; the 0-60mph time is claimed to be 4.4sec, and I can believe it. It is just as alive in the corners. You want smoky oversteer? You’ve got it. Likewise, it steers and handles in that most involving of ways that has made the XJ the best-driving luxury saloon, only it feels sharper still in the XJR.

On this sneak preview drive, we’ve got the whiff that Jaguar has gone and made another very special big sporty saloon. It’s just a shame my responsible and trustworthy streak kicked in and I had to give Jeff the keys back, as we’d know for sure after an afternoon blast in the Sussex B-roads around the Goodwood estate.