Which is Best Backordering Company for .co.uk domain Names?

I have had decent success with DropCatcher.co.uk for .co.uk names. If the name isn't really premium you might be able to catch it. The names that I've caught with it aren't premium, but are in my niche and I knew that I couldn't be bothered monitoring the drop myself, so I just paid for it. They have reliably caught the names that I wanted. I doubt there was any competition though. Be aware that you have to pay for drop catch slots ahead of time and they're not cheap, they're non-refundable and there is no guarantee that they will catch any name for you.

Good luck.