Oh dear....
I was going to say that the MC7737 string was a stores code (which indeed it is), and so the bag was probably artillery related, that being VAOS Section 'M'.
Unfortunately a web search when I got home turned up a real MC7377 webbing strap:
https://picclick.co.uk/Ww2-British-3...581791957.html
and it's most likely that your bags have been made from cut-up surplus webbing and fresh canvas, possibly for the fishing/sports market. (Especially since the cut-off end of the strap goes through the middle of the maker's name: Finnegans.)
Chris.