Virgin at Heathrow regularly weighs carry on luggage and seems to try and enforce the weights strictly.

- If you hand luggage is too heavy (this happened to me when I was 1kg over, having paid about £2000 for a full fare Premium Economy Ticket )the check-in staff tell you to carry your lap top as a purse to bring your carry on weight down. You then pack away your laptop back into your hand luggage and that's the last anyone seems to care