Single LED lights - advice from a motorcycle courier

Probably right. I've got a few of their lights and can reccomend the Trustfire TR 801 for London use. Costs about $20, is fucking bright (some mtbers use them for night riding) and is more slimline than the P7s so it takes up less space on the bars or in your bag. I mount mine using an inch or so of road inner tube over the body of the torch and then a 32mm O ring around the bar dinotte style. Batteries and charger also available from dealextreme.

I also got a MTE MC-E torch which is like turning on the sun. I think it would be too bright to safely use on the road as it lets you see for about 70m in the proper dark.

I was considering giving one of these a go. @ 4 watts they seem like they would be bright and there is some talk about them on candle power forums. Biggest down side is the length of them.