Police Harassment of Photographers in the UK

On a recent short trip to the UK from Zurich I was wandering around the Bloomsbury area and making my way back to St Pancras via Tottenham Court Road. There was a protest against Scientology going on, and I took the following photograph.

After walking past I was chased by the police officer shown and asked to account for myself. The conversation went something like this.

PO: "Who are you?"
ME: "My name's Richard"
PO: "You took my photograph"
ME: "No I didn't, I took a general photo of the protest"
PO: "You're a liar. You pointed the camera straight at me and took a photograph"

At this point the use of the phrase "You're a liar", the abusive tone and absurdity of the situation got to me, and it has to be admitted that I didn't feel like fully co-operating. He insisted in performing some kind of stop and account report (of which I have the evidence).

I said that it was not an offence to take a photograph, and his reply was that "He did not like his photograph taken". I suggested that he shouldn't use his police uniform to support personal whims. On asking several other questions and not apparently getting the answers he wanted he repeatedly said "You're a liar".

After a while he asked if I had been drinking. I said "Of course I've been drinking, it's Saturday afternoon". (In fact I had three pints of beer taking photos and watching sport on the television) However now he seemed to think this was important. "You're intoxicated. Very intoxicated" All of this in a loud voice and in full view of many bystanders. He wrote it in his little book.

During this whole episode my impression was that he was excitable and angry, irrespective of the disrespectful and rude attitude. He dropped my id twice on the ground, and made several mistakes filling in the form, putting his own name in place of mine for example

I was still wondering what crime I had committed. After about 20 mins I was allowed to proceed.

I have three points to make about this.

1) Why was I stopped in the first place? Teenagers are dying of knife crime in London all the time. Do something useful.

2) Why was the attitude so immediately disrespectful, aggressive and rude?

3) If this is the state of agitation that police officers get into confronted with such an event, how can the UK trust them to manage more serious affairs?

In case anyone is interested, they can see the entire film that I shot on the day here.

A quiet day in London