A climate activist who caused “mile after mile” of tailbacks on the country’s busiest motorway after climbing up a gantry has been jailed.

Jan Goodey, from Brighton, was part of a Just Stop Oil demonstration which forced authorities to close sections of the M25 during the morning rush hour on November 7.

The 57-year-old was sentenced to six months in prison at Westminster Magistrates’ Court on Tuesday after pleading guilty to causing a public nuisance through his protest on an overhead gantry at Junction 16 of the motorway.

Goodey pleaded guilty on November 8, having on September 27 received a two-year conditional discharge for obstructing the highway in a separate protest last year.

District Judge Daniel Benjamin said that Goodey had “flagrantly ignored” previous warnings that his conduct “was not acceptable in a peaceful and democratic society”.

The judge said: “I struggle to see what more the courts could have done to warn you that this type of conduct goes beyond what is legitimate and acceptable by way of peaceful protest.”

He said that to describe the disruption as “significant” was “perhaps an underestimate”, adding that the protest had caused “mile after mile of solid traffic on what is almost certainly the busiest motorway in this country”.

He added that if Goodey’s intention was “not to inconvenience members of the public” there was nothing stopping him from affixing the banner to the gantry and getting down or affixing it to a safer location alongside the motorway.

Goodey will spend half his sentence in custody, with time spent on remand deducted automatically.

He was also given a £187 statutory surcharge to be paid by July 31, 2023.

A spokesman for Just Stop Oil said: “This shows that our government would rather lock up peaceful protesters than put an end to new oil and gas.

“We know the course they are setting is going to destroy everything we know and love and that is why we must resist. We will continue to do everything non-violently possible to stop this horror. This is what Jan has done."