As the heading states I have found a supplier in Australia who is cutting down 10 round magazines to make 5 rounders. I have had my hands on one for my no1 mk1 and can inform you they are very well made, good quality and look good on my speed project. They are also blued.
I believe he said he can also make them up for the no4 rifles.

I have informed him of the forums, hopefully he will be along soon, (i believe he’s having issues joining?) otherwise for those interested he has an add up on ozgunssales