I’ve found a great cure for depression about the state of the British car industry – a trip down the M40, and a game of ‘spot the prototype.’

From the earliest days, car manufacturers have regarded the nation’s motorway network as unofficial test tracks. Indeed, when the M1 first opened, a large percentage of its early traffic consisted of sixties sports car prototypes being maxed out among the doddering Ford Populars and Morris Oxfords. Which must have been interesting, to say the least.

But, as the epicentre of Britain’s automotive R&D effort has moved, the northern stretch of the M40 has become the best place in the country to see future models being put through their paces.

A trip south yesterday produced three good sightings. A partially disguised Aston DB9 glimpsed on the other carriageway might have been hiding a mild redesign, or it could have been a One-77 prototype. Next, a heavily binbagged saloon taking the Gaydon sliproad, which was almost certainly the new Jaguar XJ.