I like a vintage Sunbeam, and although I don't own one I read each issue of "Beaming" (magazine of the Marston Sunbeam Club) after my Sunbeam-owing friend finishes with it.
My reasoning here is:
Sunbeam gave up on the Druid-style side-spring fork on most models in 1931, so the bike is 1930 or earlier.
The carrier is a type that came in (I think) in 1929, which leaves us with 1929-1930, when almost all models had a saddle tank.
High exhaust pipe says OHV, so we're down to 1929-30 Model 8/80 or 9/90.
Side valances on the front guard, standard on Model 8 (350) and Model 9 (500). The sporty Models 80/90 could be ordered to any spec, but almost all would have had sporty blade mudguards.
So we're left with 1929-30 Model 8/9.
Looking again more closely, I can see the front fork damper is on the lower fork spindle. It moved to the top spindle for 1930 models, so I reckon we can say (with some confidence) 1929 Sunbeam Model 8 or Model 9. You'd need a fab photo with no legs to tell those two apart!
I can't quite see from the photo that the tank is a saddle tank, but the carrier is a strong pointer to saddle tank (1929-on). Of course it could be a 1928 flat tanker with an updated carrier!!
Cheers
Leon