Dom Joly: Tweets to followers ratio too high? You may be a loony

My second week of hidden camera filming around the UK is over and it has taught me a lot about three of our most visited tourist towns.

First stop was Bath. If I'm honest, I was expecting this to be quite a tough place for laughs, as it has a reputation for being the spiritual home of Britain's "crusty" community. By this, I mean a white man with dreadlocks, dog on string, carrying a large bottle of cider brigade.

We used a couple of rather unsubtle tents in which to hide some of our cameras and therefore had several incidents in which rather self-righteous Citizen Smith types accosted our unfortunate camera people under the illusion that Bath was close to succumbing to some Stasi-like regime.

Day two was in Oxford. I have a soft spot for Oxford and it did not disappoint, with most of the inhabitants being both friendly and reassuringly happy to sign release forms after dealing with the rather ludicrous character I was playing. The city was, however, absolutely packed with gargantuan groups of sullen, badly dressed French schoolchildren blocking every available pavement. I'd forgotten just how deadly dull school trips could be. And once the kids had purchased a hideous sweatshirt saying something like "I love Oxford" and bedecked themselves with a pair of ugly fluorescent sunglasses, they had nothing left to do but wander around sucking on McDonald's milkshakes and seeing who can wear their trousers the furthest down their derrières.

Day three was in Cambridge and by far the worst of them all. I admit to being a little prejudiced against Cambridge, as I firmly believe that you are either an Oxford or a Cambridge person and should not enjoy both. Quite apart from anything else Cambridge is at the start of "suicide country" – the flat, depressing part of England that rolls on into Suffolk and Norfolk.

We set up on the gorgeous King's Parade, in front of King's College Chapel. And then the loonies came. It was like we'd unknowingly stumbled into some unadvertised convention for the movement.

The worst of these was a gentleman who looked as though he spent most of the day noting down engine numbers. He spotted one of our camera vans and stood in front of the window blocking our shot. When the production team politely asked him to move, he refused. He announced that he was engaged in a protest. We asked him what he was protesting about and he told us that it was "top secret".

After further inquiries, he let slip that he believed us to have been following him around the country and that he was "on to us". He was eventually persuaded to clear the camera shot, but then stood nearby making noises not dissimilar to a cow. All the time, he was busy tweeting. We found his Twitter page, and the real give-away were his Twitter statistics. He had tweeted 31,635 times and had 22 followers. That "number of tweets to followers" ratio is possibly the best indication of a person's mental health currently available. No wonder Syd Barrett moved to Cambridge; he must have felt right at home.