1903 Belt

No doubt issued to the Home Guard for the obvious reason that they were a very good design;
being a commonly issued military pattern of belt, readily available in from QM stores, wouldn't have hurt.

Another advantage of the 1903 Belt was its very simple & basic design, not having any sewing or riveting in the construction (aside from the running slider, which could be finished using either of the two methods)
(Most information on the 1903 belt design is in the link above.)

For modern users, I can supply these in a range of sizes, not just the WW1  Small, Large  & X-Large options.