Many thanks for the extra information everyone.
Dave, I know I'll probably upset some purists here regarding the wooden boxes but : Although there are people who think that old things should be left to look old & decrepit, I wanted the box to last a few years longer. The wood was very dry and had some splits starting to appear so I cleaned the box with very fine wire wool and then gave it a few coats of linseed oil to impregnate the wood with a little moisture. (Seems to work for the wife, although she doesn't use linseed oil
)
I also bought some leather straps online and made new leather handles for the AVO's & boxes. The original ones had some nasty cracks which felt like they could snap at any time, in fact one box already had a handle that had broken one end. I have kept the originals in the boxes.
I also found some crumbling spacers that seemed to be made of some sort of thick felt in the boxes, presumably to stop the AVO knocking around too much. I replaced them with some modern sticky back felt sheets cut to fit the bottom & sides so that the AVO fits snugly.
Regards ..... Gary