Goodwood Revival Meeting
also seen here:- /vehicle_270551-Matchless.html
chassis AJS 7R mais moteur on dirait du 18S!
Lambretta LI 3rd series (Nr47) The next one is a lambretta LI 1st series
Moto Guzzi 350 Grand Prix Episode: 4
Looks like a Moto Guzzi 350 Grand Prix racer from around '50
Honda CR450 Episode: 4
Matchless G50 Episode: 4
Velocette KTT350 Episode: 4
Need to see it from the side if poss. Indeed, very hard to distinguish. Going on the colour and shape of exhaust it might be an AJS 7R Boyracer The starting list says it is a Velocette KTT 350, which seems to be correct capacity-wise, the number plate for the 350cc class was indeed blue.
Good research! Well, at least I had the capacity right