Dom Joly: Nose... Cameras... Action! I'm Trigger Happy again

I've been filming hidden camera stuff for the last week and I've forgotten how much it takes out of you – the waves of adrenaline and the subsequent crashes are killers and I've just slept for 24 hours solid.

In the old days, I'd just put on some rubbish costume and head off with a cameraman and "see what happens". With hindsight this probably explains why it took over a year to make each series of Trigger Happy TV. Back then, the vast majority of each day was spent wandering around trying to think of something to do and then trying to find someone to do it on.

With my new filming, things are very different – it's all incredibly well organised. I'm more recognisable now, so I have to be disguised. This involves the addition of prosthetic noses, fake teeth, wigs and elaborate costumes. It's great fun becoming someone totally different, but it takes a lot of time to get there and you then tend to spend the entire day longing to scratch your real nose – like some exquisite torture.

Once ready, I step out into whatever location we have chosen to target. I have a little earpiece in my left ear so that I can keep in contact with the team, who are all hidden in vans and windows all around the place. The cameramen are hilarious – some hide their cameras in prams and stand around trying to look subtle, occasionally talking to their non-existent babies. Sometimes someone will wander past them and stare into the pram expecting to see a lovely little child. Seeing no baby, they look up, then around and then scuttle off as fast as they can. Another of the cameramen always sits alone on a bench with his camera peeking out of the end of his bag.

Because I know they are there, I feel that they stick out like very sore thumbs – they look like a gang of travelling paedophiles – but nobody ever seems to notice them.

Hidden camera often uses the same theory as bank robbery. I'm told that when entering a bank with the intention to rob, you need to make a lot of noise and take control of the situation. My "characters" normally tend to be quite unusual and attract attention – people therefore never seem to look anywhere else, and never notice the cameras. I've yet to film a stunt in which anybody spots one, which is quite extraordinary since we take over every area we film in.

When I'm about to "move in" on a target I always take a last look around – there is the pram-cam trying to look subtle, the camera on the bench pretending to fiddle with the bag, the camera in the window, the oddly parked van with the tinted windows, the two runners (always looking a bit too "London" for where we are) positioned at each end of the shoot to grab people and explain what has just happened, the gaggle of production staff with clipboards at a safe distance.... It's a rush.

I love this moment just before we roll. To everyone else there is nothing unusual going on, but I know that we are about to do something to shatter this ordinary scene. For a brief moment we are in charge of life.

Sometimes we are just part of a busy area, but occasionally everyone is working for us, so that when a real person walks into the scene we have literally altered reality – they are suddenly on the set of our very own Truman Show.

The end of the day is always the best however – tear off the wig, peel off the nose, remove the teeth, and have a long shower before getting changed back into my normal clothes. Then it's off to get something to eat and drink – back to life, back to reality.