Gosh, what an absolute treasure you have there! <3

Nothing other than what you hazarded about the word 'wound' seems to formulate.

I think it would be quite rare for people to have continued such a tradition as recording b.d.m's in a family bible (assuming they even have one these days).

I find even the handwriting, knowing it was done by family members, is a lovely tangible link to them.

(sorry if you've done this research already, but I couldn't resist trying to help date the bible)
From: https://en.wikipedia.org/wiki/British_and_Foreign_Bible_Society

On average between 6–7,000 volumes were sent out every working day for fighting men, the sick and wounded, the prisoners of war, exiles and refugees. That's over four copies distributed each minute, day and night, for the duration of the war.

There is a little about the printers, but not relating specifically to the Bible: https://en.wikipedia.org/wiki/Eyre_%26_Spottiswoode

I would imagine there was some frantic production going on during the war to get those bibles out and distributed.