The Davey-Milne Special was based on a Bugatti Type 37 chassis, the original car being imported to Australia in 1926. Reputed to be the fourth Type 37 produced in the factory, Chassis No: 37104. It had a number of owners in Australia and was entered in the 1933. 1934 and 1936 Australian Grand Prix, each time it retired in the race.
A posting from Tony Press. The link below provides a useful chart for comparing spanner sizes (a wrench in the USA) and common nut/bolt use. I found it a very good explanation of the various series of threads. Spanner Jaw Sizes by Paul Crawford - http://www.sat.dundee.ac.uk/~psc/spanner_jaw.html Cheers, Tony.