UK source of small UNC nuts and bolts?

[Tony Duell]

This is classiccmp-related in that I am repairing an old HP 
'Multiprogrammer' (a modular input/output system for HP2100s, HPIB 
machines, etc). While dismantling it I had one screw shear off and had to 
drill out pop-rivets holding a heatsink to the side casting.

So waht I am looking for is a source of small UNC nuts and bolts in 
reasonable quantites. 'Small' means 4-40, 6-32 and 8-32. I would be 
looking for countersunk and pan head scewws, nuts, lockwashers, etc. 
'Reasonable quantities' would be a bag of 100. These are not at all 
common in the UK, we tend to use BA (older machines) or metric (M3/M4 
sizes). 

Does anyone know a company who can sypply these to the UK?  Preferably one
based in the UK (to save on postage charges), but there's no real problem
with shipping a ag of nuts and bolts from anywhere. 

-tony