For clarity, I have NO connection with this company other than having been a customer, but I like to reward good service by encouraging others to use it.
UniMaster Components in Newbury (
www.unimaster.co.uk, 01635 528692) is basically Engineering Filth - they sell hydraulic components, sexy tools and engineering fixings. Friendly people, and the prices are pretty reasonable. I've just bought 3/8 UNF manifold studs (6 off), plain nuts, and plain & spring washers (18 off each) for under £6.50 all-in (cheapest I saw online came to over £12 and I'd have to wait for tehmt o be delivered). At the moment they have a very good range of UNF and UNC fastenings (and also BSF and Whit) - and I get the impression that someone coming in for imperial stuff is unusual enough to be "interesting".
I do of course have a vested interest; if they don't keep selling enough, the imperial stuff will disappear from their range - and as they are only round the corner from me, that would be a PITA.
So, anyone within range, please give them a look whenever you need imperial bits...