Generally good advice; however, bike thieves in Stratford seem to have taken to carrying bolt cutters with them over recent months: http://westmercia.storm50.com/article/9165/Lock-it-or-loose-it

When I was at Coventry Technical College, someone stole the padlock and chain securing my mate's bike. To this day, he still thinks it was me. - It wasn't! (Though I do admit to being pretty good at 'picking' padlocks.)