I think hat is the same back brake they used on the Birmingham Scotts.
If so there was a fair quantity of these components at Holders
The Velocette Motorcycle Company
Meriden Works
Birmingham Road
Allesley
Coventry CV5 9AZ
Tel (0)1676 522 066
email velocette.motorcycle@virgin.net
Ask for David, Matt or Ron
If you prefer not, I am sure Graham Moag would enquire for you
Best of luck Roger
