Winston66
My reference book Great British Bikes, ISBN 0-7481-0020-2 page22 has an illustration of a look alike with the same exhaust and sloping timing chain / magneto drive cover, forks and headlamp and tank with kneepad and has the caption .
Ariel Red Hunter a 250 CC machine built in1936
The square Four a 1931 497CC , that is also pictured of the same era has a radicly different exhaust,but the forks and the headlight and tank look similar.
Cheers ,winston66