Thanks guys.
I can confirm it's always stored assembled and also the wood well seasoned with the original serial number stamped into the stock fore end. (1922 proof date on action & barrel)

I have no idea at all what causes the shift in ease of removal/replacement of the takedown pin!

Hopefully later this year May onwards the rifle will see a replacement Krieger barrel on it.
The original is completely shot out and it's useless for humane use on live quarry.

I have made special mention of the barrel furniture to the extremely well reputed gunsmith who will carry out the work, as all the furniture will be placed on the new barrel and the open sights regulated for accuracy as well as the 'scope fittings.

I can only hope the takedown pin/lug issue goes away in this process.
Cheers, d