There are no distinguishing badges or rank visible on his uniform. What you can say is:
a). he has the ribbons of the British War Medal and the Victory Medal from WW1,
b), his uniform is that of a soldier (as opposed to an officer) from WW2, not WW1. So likely he was in the Home Guard.
c). it might be a trick of the light or my poor eyesight but is there some sort of patch on the bottom third of his epaulette ?
Sorry I cannot be more helpful.
Good luck with your research.