Management have a handy hint for ticket sellers. If someone asks for a quid's credit to be added to their Oyster card and tenders a twenty pound note, ask them "Are you sure you wouldn't like more credit than that?".

Staff at Arnos Grove were not convinced, but dutifully followed the advice. The very first time they enquired of the face at the window as to whether he might want more than a quid on his card, the unfortunate ticket seller got a reply the polite version of which was "If I'd wanted more credit, I'd have bloody asked for it!"

So now they just take the quid and add the credit. Any managers who come up with bright ideas like this should have to test it out themselves before inflicting it on the rest of us.