The protesters were sentenced on Wednesday after they admitted breaching an injunction by taking part in a blockade at junction 25 of the M25 during the morning rush hour on October 8.
Ana Heyatawin, 58, and Louis McKechnie, 20, were jailed for three months, while Ben Buse, 36, Roman Paluch-Machnik, 28, Oliver Rock, 41, Emma Smart, 44, Tim Speers, 36, and James Thomas, 47, received four-month sentences.
Ben Taylor, 37, was given a longer sentence of six months “to deter (him) from committing further breaches” after his submissions to the court on Tuesday were described by Dame Victoria Sharp as “inflammatory” and a “call to arms”.
The judge, sitting with Mr Justice Chamberlain said there was no alternative to custodial sentences given that the group’s actions were so serious and they had made it clear they intended to further flout court orders.
Myriam Stacey QC, representing National Highways, previously said the legal costs of the contempt proceedings were just over £91,000 and she asked the court to order the protesters to pay.
But in a written judgment after the hearing, the two judges ruled while it was fair to get the jailed activists to pay some legal fees, National Highways’ claimed costs were “excessive”.
They found National Highways’ fees included sums for advice from two senior barristers, four junior barristers as well as extra fees for three barristers.
“Even bearing in mind the need to consider relatively extensive evidence… we consider that these costs were excessive,” Dame Victoria said.
The two judges also said it was not “reasonable” for three solicitors to attend the High Court hearing.
Dame Victoria and Mr Justice Chamberlain ordered each of the activists to pay £5,000 towards National Highways’ costs, making a total of £45,000.
“We would expect the claimant to enter into a dialogue with the defendants about how this liability is to be discharged,” the judges concluded.
Insulate Britain has said it intends to continue the protests, which have sparked anger among motorists and others affected by the blockades, until the Government agrees to insulate homes.
The High Court has so far issued five injunctions to prevent protesters from blocking roads.
They include four injunctions granted to National Highways, banning demonstrations on the M25, around the Port of Dover and on major roads around London and one to Transport for London (TfL).
TfL was granted a civil banning order aimed at preventing protesters from obstructing traffic on some of the capital’s busiest roads.
Those who breach the injunctions could be found in contempt of court and face a maximum penalty of two years in prison or an unlimited fine.
Further committal proceedings are expected to be issued against other Insulate Britain protesters relating to protests on October 27.