A police officer who chased and then smashed a pensioner's car window has won £440,000 after a tribunal found he left his job after becoming a "laughing stock" among his colleagues when a video of the incident appeared online.

Mike Baillon, who has now left the police, said he was ridiculed by fellow officers on a daily basis after video of him smashing the window of a car driven by 74-year-old disabled pensioner Robert Whatley went viral.

He took his former force, Gwent police, to a tribunal saying he had been constructively dismissed and had been removed from front line duties after the incident. The tribunal awarded him £430,000 for the loss of pension he would have got had he retired after 30 years service, plus £10,000 for the wages he lost since leaving the force.

In 2009, police stopped Whatley for not wearing a seat belt as he drove a range rover near Usk, South Wales.

Whatley was being issued with a fixed penalty notice by police when he drove off. He claimed he thought the officers had finished, and he wanted to get home and take medication for his heart and for a stroke he had suffered.

A police car pursued Whatley as he drove through country lanes for over 15 minutes, with sirens blaring.

Whatley's car eventually pulled over. Video taken from a camera inside the police car shows PC Baillon running to the pensioner's car, and striking the side window 15 times with a baton. Another officer clambered on the bonnet and appeared to be trying to kick in the front window. The pensioner is then pulled from the car, having expected officers to have tapped on his window.

An internal inquiry cleared PC Baillon, but his colleagues teased him about the incident, defacing his work locker with the words "Whatley incident".

Baillon told the tribunal: "The ridicule from colleagues was getting to me – it was every single day. They thought I had done wrong and I was lucky to have got away with it. I just wanted my closure."

Baillon, an experienced traffic officer, suffered from stress and his bosses removed him from frontline duties fearing his mental state might affect his performance. Baillion's solicitor, Nick Smith, told the tribunal in Cardiff that Gwent police had treated the officer poorly: "Baillon was removed from a job he loved and it was a gross abuse of power by the police.

"What has made that worse is the disingenuous way the force has defended their actions. Their conduct has been reprehensible. It is a public disgrace." Baillon said later: "I couldn't accept the treatment.

"Unfortunately it has taken so long to reach a settlement."

The pensioner received £20,000 from police for the damage to his car. He was fined by magistrates for motoring offences and ordered to pay £235 plus costs.

Baillon, a police officer for 16 years, eventually left and set up a woodcraft business that makes decorative reindeer and other products .

The Conservative MP David Davies said Gwent police should have been more effective in halting Baillon's mocking by his colleagues: "I don't like to see big payouts of this kind, I think the whole thing should have been dealt with better by the police force. There is a tendency in the police to rib people, but his colleagues were making a mistake when they made fun of him.

"He was chasing after a vehicle which had refused to stop and he had every reason to think this was suspicious."

Gwent police said they would reflect on the judgment.