What is the best lock?

Can you imagine someone wheeling a massive oxyacetaline kit down the road just to nick a bike?
thats rediculous...
you may aswell wheel it round to tiffany and nick something worth the effort.

them kind of people drive around nicking anything and everything.
they DO carry around oxyacteylene tanks in the back of a van.

Go around stealing motorbikes, scooters, bicycles, construction equipment, pieces of street furniture (for the steel). Ive seen it with myself, and I dont even live in london.