I'm on a quiet architectural stroll through London, wandering down from Marble Arch to Piccadilly, and I reach Grosvenor Square. All around are giant concrete bollards and high fencing. Well, I know what this is about, because we saw the same thing in Oslo - it must be the American Embassy. There are a few police wandering round with guns. The sky is clear and there's a really good shot of the flag against the eagle, as well as the repetitive window styling. Across the square the Canadian Embassy has none of the protection, but is catching some of the setting sunlight. All is quiet, and I carry on to Grosvenor Chapel. All of a sudden, two policemen on big fat motorbikes sweep up to the curb and demand my name and address. They take my camera from me and want to know if I'm a British citizen. They ask me my height and the make of the camera. They ask my job, and make a comment on the shortage of maths teachers, and how I must have seen a lot of changes in 12 years of teaching. They ask why I was taking photos and what I'm planning to do with them. They ask if I've ever been arrested or charged. They look through the photos. They radio in my details which check out OK. They explain that in the 'current climate' they have to take precautions and they're sure I will understand. They apologise for detaining me and drive off. Without making light of American deaths, it seems to me the current climate is that George and Tony are getting very sensitive about having started a generic war against terror, and invaded a country with no clear legal basis. The chance of a terrorist attack on the American Embassy in London is extremely small, but they have no problem employing British policemen to detain and question citizens in a public place where there is no notice or law forbidding the taking of photos. Maybe I should have stood up for my rights, perhaps if Sarah had been there I would have done, but in the current climate I can't take any chances with the police. So if you're passing Grosvenor Square, make sure you're (a) British, and (b) not bolshie.