Many thanks to the Lamb and Dog Walker for their sterling efforts. Sadly though, my vest is far too big for me. I ordered a M44 (given that my normal tops claim to be 42/44 and the forum vests were rumoured to be a bit snug) but it's ridiculously big.
So, is there anyone out there with an M40 or M42 vest they'd like to swap? Or alternatively, if anyone wants an M44, I'll gladly pass it on.