Do you mean manufacturers or suppliers?
There are two companies that import stuff that are still relatively small. Superstarcomponent and Discobrakes. I know very little about disco brakes other than I like the pads. Superstarcomponents are growing rapidly increasing the product range all the time. They had some initial bad press but they seem to be putting that behind them from what I’ve read on other forums. I’ve had some stuff and I’m impressed. Think my next set of wheels will be coming from them. It’s not UK made though just bought in the far east and branded. It’s the bling stuff at low prices that makes them popular.
I’d love to know about clothes manufacturers. I’m always pretty impressed by cycle-clothing.co.uk stuff given it cost far less than the competition. Would consider it low end though good enough for everyday riding but not my Sunday (club run) best.