Dip into Babylon (Channel 4, Thursday, 10pm) for a few seconds and you might think it is any number of things: a documentary about an armed police response unit, a 24-hour running news programme, or maybe even a drama about a troubled police commissioner.

You would have to watch it for quite some time to realise that it is, in fact, a comedy and one other thing too: a programme that has probably got closer than any other to what the police are really like.

Anyone with friends or family in the force knows the reality: the police are not always committed, brave and courageous; some of them are bored, some of them hate their job, some of them are useless.

But almost all of them use humour - of the blackest, darkest sort - to get through the day.

Documentaries, and even gritty police dramas, do not usually reflect this and often portray officers are either corrupt or angelic, but Babylon is different and puts humour next to horror, as the police do every day.

There are prison riots, there is death, violence, abuse, there is even the shooting of a horse, but all the time there is humour and absurdity too.

As the riots break out, for example, the police are gathered round a screen watching CCTV coverage of the prisoners running amok and the main concern of the police is what to call it. "Bottom line, is it a riot?" asks one.

"Well, it's a disturbance," says another. "Disturbance is fine. In my opinion, what we're looking at is a severe disturbance."

Later, when the police are gathered round a walkie-talkie negotiating with the prisoners who have taken their warders hostage, the prisoners demand that food be sent in, specifically stuffed crust pizzas.

"Not stuffed crust," says one of the officers. "That's taking the p***."

Later, at a press conference, the press want to know what the toppings were.

Babylon, which features James Nesbitt as the chief constable, is not the first to mix policing and comedy (Rowan Atkinson did a sitcom called The Thin Blue Line in the 1990s and the BBC is currently running one called Scot Squad) but those shows make no attempt to reflect reality.

What makes Babylon exhilaratingly different is that it does: the pictures of the prison riots look properly violent and real and you laugh and then you ask yourself, 'Should I be laughing?' and then laugh again.

The writers of Babylon, Sam Bain and Jesse Armstrong, did much the same on The Thick Of It, which they also wrote and which greatly resembles Babylon in tone and execution.

Babylon's creator Danny Boyle also added an extra layer of varnish by directing the pilot in February and the directors of the series have managed to maintain his pace, intensity and wit.

But its greatest quality is its honesty and the fact that, just as The Thick Of It did with politicians, so Babylon does with police officers: it laughs with them, and at them, and it points out that professionals are much less professional than we think.

Their job is to pretend otherwise; Babylon's job is to laugh at their absurdity.