Two Just Stop Oil protesters jailed after scaling a bridge on the Dartford Crossing have lost a Court of Appeal bid to have their sentences reduced.

Morgan Trowland, 40, and Marcus Decker, 34, were jailed after using ropes and other climbing gear to scale the Queen Elizabeth II Bridge, causing gridlock when police closed it to traffic last October.

At a hearing in London last week, the protesters’ lawyers made a bid to challenge the “extraordinary length” of Trowland’s three-year sentence and Decker’s jail term of two years and seven months.

But in a ruling on Monday, their appeals were rejected by three senior judges, who said the sentences were “not excessive”.

Lady Justice Carr, sitting with Mrs Justice Cutts and Mrs Justice Thornton, said: “This was very serious offending by repeat protest offenders who were trespassers and on bail at the time. Whilst the protest was non-violent as such, it had extreme consequences for many, many members of the public.

“Mr Trowland stated in his evidence that ‘the warning message is dependent on disruption’.

“The grave consequences that we have described were not only inevitable, as the protesters would have known, they were precisely what the protesters intended and set out to achieve.”

The judges acknowledged the “long and honourable tradition of civil disobedience on conscientious grounds” and that the sentences handed to Trowland and Decker went “well beyond previous sentences imposed for this type of offending”.

But Lady Justice Carr said the jail terms reflected “Parliament’s will” under new laws enacted under the Police, Crime, Sentencing and Courts Act last year which introduced a new “fault-based public nuisance offence for what obviously will include non-violent protest behaviour, with a maximum sentence of 10 years’ imprisonment”.

She said the sentences met the “legitimate” aim of deterring others from such offending.

The judge added: “The sentences should not be seen as having a ‘chilling effect’ on the right to peaceful protest or to assembly more generally – deterrence and ‘chilling effect’ are not the same.

“This protest was of a wholly different nature and scale to the many non-violent protests of conscientious activists up and down the country exercising their rights to freedom of expression and assembly on a daily basis.”

Daniel Friedman KC, representing the activists, had argued their jail terms were “the longest ever handed down in a case of non-violent protest in this country in modern times”.

Their trial at Basildon Crown Court was told the bridge was shut from 4am on October 17 until 9pm the next day, sparking traffic jams as motorists were forced to use tunnels instead.

Structural engineer Trowland, of Islington, north London, and private tutor Decker, of no fixed address, denied causing a public nuisance, arguing it was a protest.

Their trial was told the protesters ascended to a point close to 200ft above the road and unfurled a “giant Just Stop Oil banner” and “rigged up hammocks and stayed there”.

The men came down at about 5.30pm on October 18 “with the help of police and a very tall cherry picker crane”, but the bridge, which links the M25 in Essex and Kent, was not reopened to traffic until later.

Essex Police said those affected by the disruption included a “heavily pregnant woman who needed urgent medical help”.

Another person missed the funeral of their best friend of 35 years, the force said, and a business lost more than £160,000 in earnings.

In April, a jury unanimously found Trowland and Decker guilty of causing a public nuisance.

Just Stop Oil previously said sentencing Judge Shane Collery KC was “trying to set a precedent” and “deter people”.

The environmental campaign group said Decker, a German citizen who it said has leave to remain in the UK, faces deportation after serving his sentence.

Trowland has six previous convictions relating to protests, while Decker has one, with lawyers for the pair previously saying they would not take part in further disruptive protest.