I have used all of these suppliers ...and if you have used good ones I'll add them to the list...Andy
MACC MODELS good for metal, nuts and bolts. tools and steam fittings etc reasonable prices and very quick service.
BA BOLTS bolts nuts grub screws taps dies rivets...metric and imperial
GLR KENNIONS for all model engineering supplies. http://www.glrkennions.co.uk
CHRONOS vast range of engineering tools Prices include VAT and postage
http://www.chronos.ltd.uk
RDG TOOLS Mytholmroyd : large range of lathe and milling tools etc
STEAM FITTINGS pressure gauges etc http://www.steamfittings.co.uk
TRACY TOOLS tap and die specialists, mills, slot drills http://www.tracytools.com
THE TAP AND DIE Co http://www.tap-die.com
EKP Supplies : screws studs nuts materials https://www.ekpsupplies.com/
CUP ALLOYS silver soldering materials and advice http://www.cupalloys.co.uk
PHOENIX PRECISION PAINTS http://www.phoenix-paints.co.uk
all railway paints, excellent quality , expensive ..postage costs a lot.
Recommendations from Lyndon Smith:
WESTFIELD FASTENERS https://www.westfieldfasteners.co.uk
Great for bulk packs of stainless screws, metric fasteners and suchlike for outdoor use. It's where I bought all my track fixing No.4 Philips pan head stainless screws from for my tracklaying.
MODEL FIXINGS https://www.modelfixings.co.uk
I have used these for various RC fixings, plus small allen keys and other useful tools
SHOP - APT https://www.shop-apt.co.uk
I have used these many times for lathe tool inserts. Best place I have found for prices and ease of choosing the right specification
GS PRODUCTS https://www.gsproducts.co.uk
I ordered all my stainless steel turnbuckles and shackles from here for securing my steam up boards. They were the best price of anywhere I found. Lots of other useful stainless fixings for the garden.