Postcodes not required, naturally, but if you've got a preference on what padlock and chain, or disc lock, it'd be good to hear about it! Share the knowledge n all that.
I myself use an ABUS chain with an Ingersol padlock. The sort of padlocks used to secure Armouries on military bases.. It does the job, I guess you could say!!
Also, HOW do you use it? Round the front wheel? round the back? thru a wheel and round the chain and shock?
I tend to wrap mine thru the rear wheel and the chain securing it to a suitable place off the ground. Ive always been wary of leaving the chain on the ground - it allows the thief to use the ground under it as a workbench while they try and nick yer ride.

So.. Hows about you lot?