Here's an update on the problem. Thanks again for all contributions, and an interesting discussion on the merits/demerits of various types of linseed oilicon.

Scary to think of all the time I've used Ace Hardware toxic BLOicon. I guess what the ravages of time have failed to do to my nuts, Ace will have completed!

Edward, I found the exact same brand of LO at the artsy craftsy store as per your photo. Thanks for that. I have used it repeatedly on the stock, and it seems to go on a lot better, and give a nicer result. Must be the removal of the fatty bits as you describe. I think that although it is more expensive, it is worth the difference for the better results.

Smellie, you were bang on. I don't know how I missed it on first inspection, but there indeed was what I assume to be the Damned Crack. Vertically down the rear face of the stock, just slightly left of centre. As you said, where the wood is at its thinnest due to the trigger channel.

So I used a previously reliable wood glue to bond it together. Quick range trip. 8" vertical movement. Back home and strip the rifle - the crack had opened up.

So I took the advice and used an Epoxy. Thoroughly cleaned and degreased first, forced as much into the crack as I could, clamped it and cleaned it up the next day. Quick range trip, only for a repeat performence. It has opened again.

I can't think how I can bond it any better than my attempt with the Epoxy. It is almost as if it needs some cross-reinforcing. I'd hate to do that, it is all still nice and standard (except for the crack).

Has anyone any helpful hints so that I can make the repair last?

Thanks again to all.

Cheers.