My big 30s Enfield cush hub has 11/16 Cycle thread nuts.
Try finding those in the local hardware !
I'd suspect your axle has been remade ?
A smaller axle I had remade was 26 tpi British Standard Cycle thread
(Or CEI, before it was renamed in the late 1940s)
For Rex, depends on the variety of your herd.
Commandos are UNF in the cycleparts.
This from W. Marples Sheffield for checking diam sizes of BS (British Standard) bolts.