Thanks all for the thoughts so far. Yes, I have ruled out Red Cross now too.
Thinking about this, the photo was probably inter-war, when he may have had a few diferent jobs including, apparently, a stint in Australia working (according to family lore) on the Sydney Harbour Bridge!
The suggestion of a hotel employee is interesting; he was a labourer and ex-policeman so I wouldn't rule out any number of jobs.
As for the embossing - that is all we have I'm afraid. It's the wrong proportions for a (modern) passport photo but I guess it could be that?
Thanks,
Neil