I bought one of Moore's replica straps for a No. 8 MK. I case. It fit perfectly. By the way, the straps are short if one is thinking about carrying them in the field. I cannot recall seeing a single photo of one being carried in the field.

To open the case one must slacken off the strap on both sides.

There must have been a lot of Armourers with secure trousers because most of the straps are missing from the No. 8 MK. I cases that I have seen.