I leave my bike locked on the bike racks at my local railway station between 7am and 7pm and so far I haven't had any problems, but I've heard of people finding their bike locks superglued (or otherwise sabotaged) so that they can't unlock their bike, so they leave the bike overnight and someone comes along later with an angle grinder to work on the lock when there's no-one else around.

Is there any way to prevent a lock being sabotaged in such a way? Other than having your own cordless angle-grinder, what other options are there?

Carry a small container of acetone with you. If you get the superglue treatment, just use the acetone to dissolve it and be on your way. OTOH, you could stake out the bike that night and whomp on the thief.

That's an interesting tactic, but all the police need to do is wait. Folding bike and take it in the train would also work.

A tacit that is occasionally seen in Chicago is the person returns to a their bike locked up with a foreign lock on it. The thief hopes the person will leave it alone until the next day. Of course, leaving a bike overnight for 10 hrs in Chicago is not very wise.

My first thought as well...

With a couple of friends and someone with a good video camera. Remember, video or you didn't actually get them.

Bold, IMO, is leaving a bike locked up out in public for 12 hours. I guess I'm so used to thieves and vandals here in the States that it would not even dawn on me to do that. Not if I counted on that bike getting me home over a significant distance.

I'd never leave my bike locked at a public place like that here in the U.S..

I like the acetone solution. Would dissolve any glue and you'd be on your way.

Finding a foreign lock holding your bike hostage would result in a call to the police. I imagine they'd be quite interested in capturing a thief.

I prefer the vigilante approach; the courts would never pass a sentence strong enough for me.

Nothing says "NO" like a Louisville Slugger...

The OP may prefer a Kookabura Kahuna