T73
You've done enough for the point. Well done.
It is indeed Chris Lawrence in the car built by J A Pearce Engineering to contest selected races in the 1966 "Return to Power" F1 season. Suitable cars were few and far between, and the team reckoned, I suspect, that they could obtain entries and thus starting money by "filling" the grid.
The website for the company claims that the car is the one driven by Bruce McLaren to victory in the 1964 Monaco GP - utter rubbish as Graham Hill won that year. It is in fact (according to the usually infallible Doug Nye) chassis T73-F1-2-64, the car driven for most of the season by Phil Hill with very little success. Into this they shoehorned what they thought was the engine from a Ferrari GTO, which they had bought from Chris Kerrison, and which was fitted beforehand in his Drogo-bodied Ferrari GT road/race car. What they did not realise is that Kerrison's car was in fact a rebodied 250GT SWB, and produced considerably less horsepower than they expected.
The photo is taken, as you said, at Brands Hatch during the 1966 British GP.
(The car was destroyed in the infamous "Pearce transporter fire" - very rum do, that. Best say no more....)
.
