Thornycroft discontinued the 10hp for 1905 and introduced two new cars, both powered by water-cooled, in-line "fours", the 4,650cc 24hp and the 2,715cc 14hp; the latter had an advanced sohc engine with a five-bearing crankshaft.
The 14hp car was built for the Isle of Man TT Race and was introduced during the summer, so it may not have been intended for sale to the public. Two 14hp cars were entered for the 1905 TT Race; car no. 12 was entered by Tom Thornycroft and no. 47 was entered by G V Baxendale, but there were no wins for Thornycroft that year.
Surprisingly, the normal speed of the 14hp's sophisticated engine was only 900 rpm, less than the 1,000 rpm of the more prosaic 24hp car with its simple T-head engine. Ignition on both 14hp and 24hp cars was by LT magneto, in which, remarkably, make and break took place inside the cylinder! Although crude by modern standards, LT ignition was commonly used at the time.
Both 14hp and 24hp had forced lubrication by an engine-driven pump - a major improvement over earlier cars' splash lubrication.
24hp Thornycroft on the weighbridge at a Hereford hill-climb
Thornycroft regarded an order for a 24hp Double Landaulette from HRH Princess Christian of Schleswig-Holstein as a publicity coup. Princess Christian, one of Queen Victoria's daughters and formerly Princess Helena before her marriage to Prince Christian, took delivery of her car in 1905. The Thornycroft sales register records that the only 24hp Double Landaulette delivered in 1905 went to a J Hegel on 18 September as vehicle no. 512. This may have been Princess Christian's car, in which case J Hegel would have been an agent accepting the car on her behalf.
HRH Princess Christian's 24hp Thornycroft