Image caption London bus driver Dave Sherry commutes for part of his journey to work on a bike with a 120 dB lorry horn

When Dave Sherry goes to work, he sits astride a bike armed with three separate cameras and a 120 dB double-trumpet lorry horn which he calls "The Pacifier". Why?

"If people want to play with snakes, they have to accept they might get bitten," says Mr Sherry, one of a growing band of cyclists whose "bite" involves posting videos of poor driving on the internet.

Some claim the rise of the camera-clad cyclist (and in-car camera) is a response to police resource cuts; others, including the RAC, believe it is a response to a growing number of bogus insurance claims.

When BBC Inside Out asked every police force in the east of England about highway patrol hours, it emerged no constabulary collated such numbers.

What is confirmed, however, is that police forces are now using publicly-supplied footage to secure convictions.

Media playback is unsupported on your device Media caption BBC Inside Out reveals how small cameras are catching professional drivers who drive badly

Mr Sherry, 37, of Harlow in Essex, says his videos - all filmed during a 40-mile round-trip commute to the train station - have led to more than 70 convictions for a variety of driving offences.

But his filming has had repercussions.

He has been driven off the road, sworn at, subjected to dangerously close passes and physically assaulted - all of it caught on camera.

"It's like a minor war zone out there," says Mr Sherry, who drives buses in London. His call to arms came three years ago.

"Some idiot drove into the back of my bike. I was late for work and I got penalised for that. I called the 'old Bill' but at the end of the day it was my word against his.

"To make it fair, I started putting cameras on my bike and helmet. Riding a bike on the road is a right and cyclists are not second class citizens.

"I'm not doing it for the money or for my ego. I've got people who despise me, I've had people stalking me."

Mr Sherry, who has filmed both drivers and other cyclists, balks at the vigilante label.

Image caption Footage shot by Dave Sherry has led to more than 70 convictions

"I just gather the evidence. It is down to the police and the courts to do what they do."

Yet he does accept that broadcasting the errors of others on the internet is a form of punishment.

"YouTube is like the public stocks. It is there for everyone to see."

One of Mr Sherry's films, which showed a bus driver using his mobile telephone, led to the man losing his job.

Mr Sherry is unrepentant.

"Drive courteously and you won't end up on YouTube. I do what I believe is true and just. If I save one person from an accident or encourage bad drivers to respect other road users then it is worth it."

Matt Stockdale set up the policewitness.com website after a near fatal accident involving a lorry. He posts examples of bad driving on the site and forwards the worst examples to the police. He claims to have helped secure dozens of convictions.

"The police and their budgets and the austerity measures are not going away," he said.

"We can all sit about and moan and say the police do nothing or we can do our civic duty and help the police. The police cannot do things unless they have the evidence.

Image caption Matt Stockdale, founder of policewitness.com, said people should do their "civic duty" and provide evidence of the worst types of driving to the police

Not every example of bad driving can be filmed from a bicycle or car.

To see inside the cab of a lorry, it takes another lorry - which is why some police forces have taken to patrolling the highways in their own unmarked police trucks.

"We've seen drivers cooking their dinners on a little camping stoves on their centre console, it burns away while they are heating their soup," said Sgt Scott Lee-Amies, of Suffolk Constabulary.

"We've seen drivers with the cruise control on... with their feet up on the dash - meaning there's no way they will be able to hit the brakes in an emergency - and we've seen other drivers on their tablets and we've zoomed in on them physically checking their Facebook."

But what does Sgt Lee-Amies make of the likes of Mr Sherry and Mr Stockdale?

"I've dealt with a few cases (where people have sent in their own footage) and I have no problem with that," he said.

"The more severe cases we have taken up and used that footage in prosecutions."