Definitely better to let it go with the benefit of hindsight. I was a bit luckier, while waiting outside Notting Hill tube one midweek lunchtime. Couple of lads helped themselves to a bike from the rack and I told them to leave it. THey only had to threaten me with the croppers and I decided calling the police might be a better plan.
Police didn’t turn up, but the owner of the bike did. I explained where her bike had gone and just got a withering look as if to say, well why didn’t you bloody stop them?
The exact same week I also got involved after watching some kids pushing a then-new KTM supermotard across a park in NW London, until I realised I was going to get a kicking from a load of 14 year olds so rang the police again. Who, naturally, didn’t turn up so I gave up after waiting an hour.
Can’t be bothered with all that again.