Seven climate activists who glued themselves to the road outside the Natural History Museum in south-west London have been convicted of obstructing a highway.

Ambulances, buses, delivery vans and a vehicle carrying a 90-year-old in need of medical assistance were caught up in the traffic in Cromwell Road, South Kensington, on 19 October last year.

Stephen Jarvis, 67, Lora Johnson, 38, Benjamin Larsen, 25, Rachel Payne, 71, Anna Retallack, 58, Benedict Sansam, 38, and Shelia Shatford, 67, were part of a group of 17 people who glued themselves to the road.

The Just Stop Oil activists denied the charge but were convicted after a two-day trial at Westminster magistrates court.

The district judge John Law said on Wednesday: “The truth is there was no prior investigation by the protesters into what the overall reaction would be. It is accepted the protest did not achieve its primary aim … and there was no change in government policy. Although [this protest] intended disruption, this was clearly a peaceful protest that involved nothing other than wilful obstruction.

“And it is not in dispute they did it in their honestly held beliefs … In this case I find the interference caused by each defendant to be proportionate and I therefore find each guilty of the charge.”

PC Daniel Woodley told the court earlier: “I attended the scene after receiving reports of people sitting in the road.

“There was a lot of grievance from drivers, words to the effect of, ‘Can you just run them over?’ and ‘They had done this yesterday.’

“There was one vehicle with a 90-year-old in need of medical care who was held up in traffic.”

Some drivers referred to the protesters as “numpties”, and two people asked why the protesters could not be run over, to which the officer, in an attempt to defuse the tension, joked: “I would rather you didn’t.”

A nurse responsible for the medical care of a 90-year-old was permitted to carry out a U-turn to redirect her journey.

Jarvis sobbed in the dock as he said gluing himself to the road was important to him as a Christian and that Pope Francis had expressed his support for fighting climate breakdown.

Retallack said the protesters needed to be in the road to cause disruption. She said: “There’s no point sitting on the side of the road as no one’s going to look at you, talk to you. We had so much positive interaction with the public that day. They wouldn’t have asked us those questions if we weren’t disrupting.”

Jarvis and Larsen were each fined £200 and ordered to pay £200 in court costs with a victim surcharge of £80.

Johnson, Payne, Retallack, and Samson were each sentenced to a 12-month conditional discharge and ordered to pay court costs of £200 and a victim surcharge of £26. Shatford will be sentenced on Thursday.