Wow, what an inventory! At a quick reckoning, way over 20,000 pounds worth in stock! Never knew T&T were that big, I always pegged them to be mainly a race preparation shop, in the way of the many similar shops in the US.
I think most would be 'on commission' sales, Michael. Title - and the car - retained by the owner until sold, but with T&T doing the legwork of marketing and advertising. Probably more effective, easier and cheaper for the owners than arranging their own small ads in The Motor, The Autocar, Speed and Motor Sport.
During the war years they operated a large warehouse in an undisclosed safe location 'near Brooklands' which accommodated many road and racing cars that had been laid up 'for the duration', including the Napier-Railton, the Barnato-Hassan, Reggie Tongue's Maserati 4CL and Goldie Gardner's MG EX135. Possibly the Cobham premises mentioned at the foot of the advert. They also developed interesting sidelines building components for Noel Macklin's Fairmile boat company and in refurbishing parts for crashed Luftwaffe planes which were being rebuilt for evaluation by the RAF's special 'enemy aircraft flight' - AKA the 'Rafwaffe'. There was at least one other similar storage facility for cars in the multi-storey car park at the Olympia Exhibition Centre, run by Metropolis Garages. Its 'residents' included Eddie Hall's TT-winning Bentley and Ian Craig's Bugatti T50.
