Hi Jamjar,
Thanks for the links, I thought it was a 1927 BSA S27. The body(?) (where the BSA is written) seems quite distinctive What do you think?
I believe the photo was taken not long before he got married in 1934 but there is no date on it. The number plate might imply that he was living in Katanning - "KA 117", in which case he was there 1930-34.
A