Well, I've just done Toronto to Heathrow with BA and had no problems, probably had 6 batteries in my handbag with no problem. Also, used it on the plane quietly making sure I let out as little vapour as possible and had no problems. Came back yesterday from Glasgow to Heathrow and Heathrow to Toronto. But the Glasgow to Heathrow route had a problem. Got thru security the first time no problems, but due to defect in plane had to go through security second time. This time they went thru my handbag very politely. I mentioned that it was probably due to my electronic cigarettes....he said "Aye, no problem" took out one of the batteries to look at it and then sent me on my way.