Chris, you may know this already!
In Bury St Edmunds market there is a gentleman named Peter Wilson who runs a tool stall for the likes of you and I.
It’s a veritable Alladins cave and it’s worth paying him a visit he may well have the bits you need.
He is there on Saturdays only but take some extra cash, I always walk away with far more than intended because of the absolute bargains he has.
Sort of stuff he has: measuring instruments, cutters, reamers, drills, taps and dies, small mills and lathes, lots of accessories for the same, the list is endless.
Checkout his box of assorted metal, brass and bronze particularly selling about half the normal price.
Len. P.