I know that I've mentioned this before on the other forum but in our big Base Workshops in Malaya where we overhauled many, many hundreds, probably thousands of No5 rifles that from about 1968 or so, all of the butts and fore-ends that were supplied to the UKMoD by the gun trade were converted No4 butts and fore-ends. These were wrapped in Westly Richards packaging over-wrapped with the Donnington 'EXPORT TRADE PACKAGE' label. The fore-ends were all Mk1 types to the exact shape and spec of the No5 with a small neat patch glued and pegged into the what would be open recess at the front. They were so neat that they'd be hard to see unless you knew.
But please, please......., if you remove the awful end cap, DON'T replace it. They're rust traps. At the first sign of rust, we'd punch out the brass top to bottom rivet and make off the wood to the cap-less contour. Once there was rust there. I don't suppose rust/moisture is a problem in the rest of the world like it was there.
Anyway, there you go............