Glazier or locksmith?
His protective overall and boots must indicate some physical risk of injury without them. The left hand has a flat palm, presumably for fitting/holding something flat in that hand.
Too clean or over-protective for a painter/decorator?
Is there a flat on the fingers of the right hand?
Blacksmiths tended to wear aprons, but this might be a metal-melter rather than former, but I don’t think that would be my favoured guess.