Sparrowman says
I also had my M&S bag declined at Glasgow security - was told that it had a volume of greater than 1 litre???
I have since been using SecurityWashbag
and have not had a problem at any airport so far, but don't hold me to that - you just never can tell with the muppet show who run airport security in the UK.............
My securitywashbag.com was rejected at STN one day and a week later was accepted as being OK.
There's no pleasing some folk!!