I saw a poor (American) guy a LHR last week who only had his laptop (without bag) and a small bag with his travel docs, passport etc.
He was given the alternative by the BAA jobsworth at flight connections to either check in his laptop (without bag) OR his travel docs bag...
...and the madness doesn't only happen at LHR but also at DUS where the security staff confiscated a 12 pack of Ferrero Roches, as they are filled with liquid chocolate...the lady enforcing the rule did however state: "Sorry, we didn't make up this carp. It isn't fun for us either enforcing stupid rules".