The world of Britain's transport police will be uncovered in a new BBC documentary.

"Quite a few people don't know we exist," said PC Bob Gee of the British Transport Police (BTP), or Rail Cops as they have been dubbed in the four-part series.

When people look at this series, they will see that we're not a bad bunch PC Gee

With just over 2,000 officers, the BTP may seem small in comparison to some forces, but their patch is the biggest in Britain.

"From John O'Groats to Land's End, if there's a railway track, we have got to cover it," the 41-year-old officer said.

'Humour'

With five of his colleagues, PC Gee will be raising the profile of the force in the series, which follows them in all aspects of policing - from dealing with death and violence to illegal immigrants and naughty schoolchildren.

"People seem to think that, because we wear a uniform, we don't have a sense of humour, which is far from the truth," said PC Gee.

"But we are approachable and we are human beings. We just have a difficult job to do. When people look at this series, they will see that we're not a bad bunch."

The action takes place in summer 2002, when PC Gee, a father-of-two, was stationed in Kent.

He was volunteered for the series by one of his bosses.

"I wandered in and he said 'here's a good subject you can film'."

He said he soon settled into being followed by a crew.

Media circus

"Half the time, I didn't know they were there. None of it is acting. What you see is the genuine article."

Transport Police look after thousands of miles of track

PC Gee's team got caught up in the media circus at Dollands Moor freight depot, where up to 60 illegal immigrants were arriving on channel tunnel trains every day.

"There would be about 15 camera crews racing up the side of the track, filming them jumping off," he said.

In one scene, PC Gee attempts to communicate with a group from Moldova, Iraq and Afghanistan.

"You use sign language. It takes a little time, but they tend to understand," he said.

The series also deals with death on the tracks - known as a "one under".

"You just have to switch off from the human element," he said.

Under pressure

"At first, you have to establish whether it is suspicious. If it is, it's a crime scene."

PC Gee said the officers are also under pressure from rail companies to get the tracks cleared as quickly as possible.

Having been a rail cop for 10 years, Gee has also encountered his share of accidents - such as the Ladbroke Grove crash.

"I ended up working in the temporary morgue, documenting the body parts as they came in."

'Street catching'

It is undoubtedly a stressful career, but he said the most frustrating aspect of his job is the red tape.

"Just by reporting a busker, I've got about two hours of paperwork and computer input.

"That's two hours I could be out on the street catching pickpockets and robbers."

Nonetheless, he is passionate about his work.

"I've got this inbuilt thing. I have to help people. It's a copper's instinct.

"If I see an offence being committed, I take it personally. The rules are there for a reason. If people break them, somewhere along the line, there's a victim."

Rail Cops starts on BBC One at 2235 GMT on 28 January.