I usually take a couple of those sealed bags and put everything in there and then put that in the bag as illustrated. At one stage, T3 was not allowing these sturdier bags and as I was going through to be driven to stand we had to go through there (circa 2010) I was in full BA drag as I was going to work off standby. I had to put everything in a sealed bag. T5 were fine - then they kicked off with the same thing. So I wrote to my MP to inquire why there were different criteria within the same airport. The reason was that a different security company was in charge of security.

I'd get one of those bags if I were you - they survive far better and nowadays they are fine with them.