Er, toothpaste. Going through security at Stansted today on my way to a symposium in the Hague, I was asked if I had any liquids in my hand luggage. I answered cheerfully “no” because I hadn’t. But then my carry-on bag was diverted for the full treatment and opened for examination. After a while, the nice lady doing this pounced on my tube of toothpaste and said “Ah! This is what triggered it”. “But”, I said politely, “that’s a paste, not a liquid”. “I know”, she replied, “but the rule is, if you can spread it with a knife it’s a liquid”.

Afterwards, I wondered why this hadn’t happened before — and realised that generally toothpaste goes in the checked-in luggage. You learn something new every day.

Curious, too, the symbolism in learning this on the anniversary of 9/11!