Remember fairly clearly the Harvard being referred to as a "Granville" with Granville being played by the Roof Fairy (Gus Mecurio). Erm, I was assuming this made it a GB. There was a Granville in the race (as well as a Vega):
Entry 46 Nominated by Mr. Clyde E. Pangbourn / U.S.A.
Granville Monoplane / Pratt & Whitney 'Hornet' 675hp
Miss J. Cochran / Mr. W. Smith - withdrew Bucharest
No idea what it looks like, even after extensive research (as in 5 min in Google, a glance through
The Air Racers by Terry Gwynn-Jones and 5 min of chin-scratching)...