sorry to hear that... really a BIG lost ! darn....
reading your case reminded of my bro-in-law... exactly the same scenario happened, but that was several years back, happened at CarreFour Seberang Prai, Penang.
that time... he lost his wallet, and also luckily not car key as well.

I found out that it's kinda WEIRD that the "hanger" is at the back of the "seat", not in front... I think may be you should make complain to TESCO so that they would change the "hanger" to the toilet's door...

You may be need to check out if all the toilets if all the hangers are at the back, not a the toilet's door there. Just afraid some purposely make the front one damaged, then put a "fake" hanger at the back.. so that it would be easy for the theft to take action !

May be next time you should fold your pant and just put on top of the toilet's tank there if it was a seat toilet.

Hope all of us learn from the story... again sorry for the lost...

to all especially with gadgets stuffs.... make sure next time whenever you go to toilet for your "business".... better ENSURE that the hanger is at the back of the toilet's door....

Otherwise... this would give chances to the bloody bugger !