A climate change protester has been jailed for five weeks after blocking traffic on the M4.

Stephen Pritchard, 63, was sentenced at Inner London Crown Court for his part in an Insulate Britain demonstration in 2021.

He was convicted by a jury of causing a nuisance to the public when he, along with three others, stopped traffic at Junction 3 of the M4 on 1 October, 2021.

The protest saw some demonstrators glue themselves to the tarmac on the road close to Heathrow Airport in west London, disrupting traffic flow in both directions for two hours affecting more than 10,000 people.

Pritchard’s co-defendants – former probation officer Ruth Cook, 71, gardener Roman Paluch-Machnik, 29, and carpenter Oliver Rock, 42 – were each given six-week sentences suspended for 18 months on the proviso they do not offend again.

The three protestors were also ordered to complete 100 hours of community service.

Judge Silas Reid said Pritchard, a former parish councillor from Bath, was jailed because he told the court he would not stop taking part in disruptive protests as a matter of “conscience”.

The judge told Pritchard: “It is not appropriate for me to suspend the inevitable sentence… you will serve up to half of your sentence in prison.”

The other three defendants said they were deterred from future protests by their experiences in court and prison.

Speaking to all four defendants, Judge Reid said: “None of you have shown any remorse for your actions and in fact wear them with pride.”

He said they had shown a “level of planning and sophistication” through the fact they had “been to the scene the day before on a scouting mission”.

Judge Reid said there was no evidence emergency vehicles were delayed by the protest but added there was still a risk they could have been “caught up in other congestion around the road”.

“There was significant harm caused in this case. Well over 10,000 people were significantly negatively impacted by your actions,” he said.

“People would have lost earnings, missed appointments and potentially missed flights.

“This was a carefully planned sophisticated operation… each of you have high culpability for this deliberately criminal action.”

Judge Reid said the protesters’ sentence was reduced from around 12 months’ imprisonment because they were bringing attention to the climate crisis.

Insulate Britain said the protestors are the first to be convicted of causing a public nuisance – a common law offence which carries a maximum penalty of lifetime imprisonment.

Pritchard, a former parish councillor from Bath, previously used his speech in court ahead of his sentencing to condemn Judge Reid as “amoral” and “irrational” after he banned the protestors mentioning the climate crisis as their motivation.

Pritchard told the court he turned to protest action after he had “exhausted every other means”, including writing to his MP Jacob Rees-Mogg, signing petitions, leading sustainability projects and planting tens of thousands of trees.

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He said he felt “overwhelming sadness” about Government “inaction” on climate change.

Pritchard told Judge Reid: “I think that your rulings were amoral. I believe also they were irrational given the situation that we’re in.

“People’s lives are being lost. The only possible way I could imagine stopping peaceful civil resistance in this context is for you to tell me that this country has stopped pumping greenhouse gases into the air.

“I’m well aware of what prison is like, having been to prison. It’s not a very nice place. But I feel like I’m already a prisoner of my conscience.”