blow one’s bags

Would you tell me whether I am right with my interpretation of the expression in bold in the following sentence?

Tim said Paddy was blowing his bags about all the money he had subscribed to the war loans. (K. S. Prichard, “Golden Miles”)

blow one’s bags = pat oneself on the back

Thanks for your efforts.

Seems reasonable. I don’t know the idiom. Maybe ‘bags’ = bagpipes?