MG K3s,Amilcar, ERAs (Bira) etc. Brooklands start photo circa 1936

Not certain of the race ERAs number 2 (Bira) and 3 (unknown), Several MGs including K3 018 (BPR403) closest to camera, Amilcar and so forth.  Happy to hear from anyone who can nail down the date/race/identities on this one.
Photo available 10x7 inch or 7x5 inch (254x178mm or 175x125mm) 
Reprinted from an original period photo  in a commercial photo lab from the original slide held in our archives. The actual print hasnone of the copyright lettering present