Protesters have climbed motorway signs on the M25 in response to the extreme temperatures in the UK and what they describe as the Government’s “inadequate preparations” for climate change.

Five demonstrators scaled gantries which support overhead motorway signs in three places on the M25, causing police to close sections of the road.

A Highways travel alert was issued for Berkshire, which said: “The M25 in Berkshire is closed clockwise between J14 (for Heathrow Airport) and J15 (for the M4) due to an ongoing Metropolitan Police led incident."

"National Highways Traffic Officers are providing assistance with traffic management on scene.”

Protesters climbed signs at junction 10 eastbound near Cobham, Surrey, the Poyle interchange at Heathrow between junctions 14 and 15, and in Dartford between the Queen Elizabeth Bridge northbound and junction 30.

Bus driver Ashley Reid takes special needs children aged seven to 10 to a school in Leatherhead by travelling between junction 12 and 10 and said his pupils, who start at 9.15am, were around 90 minutes late for their last day of term as a result of the disruption.

“We joined (the motorway) just after 9am and we didn’t arrive at school until 10.45am… with their autism (they) found it difficult to understand and stay calm,” the 40-year-old, from Reigate, told the PA news agency.

“It was really disruptive and I felt so sorry for them… today was their last day before the summer break and they would all be changing classes so they just wanted to get to school and spend time with their teachers and friends.”

The children are set to finish school at 1pm, when Mr Reid will have to return to the school to pick them up.

“I am sympathetic to the cause that these people are protesting against; however, they are disrupting a lot of innocent motorists and (in my opinion) will lose more sympathy than they gain,” he added.

A travel alert from Highways England on Twitter warned: “There are delays of over an hour on the M25 anti-clockwise in Surrey due to an ongoing Surrey Police led incident within J10 (for A3, Guildford). 3 lanes (of 4) are currently closed.

“If this incident impacts on your planned route, please allow extra journey time as there is over nine miles of congestion on approach. Plan ahead, you may wish to re-route or even delay your journey.”

“National Highways Traffic Officers are providing assistance with traffic management on scene.”