Bob at some point later in the war, the forks were made 1/2" longer and that spacer was adopted to make up the distance for the mudguard attachment. It's a simple piece of 1/2" long hex (.52") with a 5/16 thread at each end. I'm sure I have one but can't look until I'm back from Netley Sat or Sun. Email me then if required.
Thanks for the information, I didn't know about the longer forks.
I'll try to find a stud commercially first, & of course one could be made.
The nature of the failure was a bit worrying. There was no indication of anything wrong but the stud seems to've been chattering in the fork lug until it didn't hold. I bodged things up by reversing the stud & with the help of Loctite it's holding. But I'll need a new one & probably a repair for the fork lug.
