Broadcaster Chris Packham has told a court he “selectively” supports Just Stop Oil but does not back all they do.

The environmentalist, 62, made the comments while giving evidence as a defence witness in the trial of 22-year-old Cambridge music student Cressida Gethin, who scaled a gantry above the M25 near Heathrow as part of a protest by the group.

Mr Packham was among those stuck because of the disruption on July 20 2022 – a day after the UK’s hottest temperature of more than 40C had been recorded.

He told Isleworth Crown Court in west London he came to “sympathise” with the fact he was forced to think about climate change while stuck for four to five hours on a trip from Hampshire to Surrey, where he was working on the BBC’s Inside Our Autistic Minds programme.

Under cross-examination by prosecutor Neil Griffin, he insisted his support for Just Stop Oil is selective and conditional.

The prosecutor asked: “You are not an independent witness, you support Just Stop Oil.”

Mr Packham replied: “I support some of their actions, selectively.”

The prosecutor continued: “You support them (Just Stop Oil), they love having you as a public figure?”

Mr Packham replied: “I selectively support things that they do. What they make of my support is up to them.

“I probably don’t support them in the way that they want.”

The prosecutor asked about a Just Stop Oil press release relating to the Channel 4 documentary Is It Time To Break the Law?, which Mr Packham presented.

He insisted the press release had been “inaccurate”, that he had not advocated breaking the law and the programme would not have aired under broadcasting rules if he had called for law-breaking.

The defendant, who represented herself, asked Mr Packham in her cross-examination: “What were you feeling (when you were stuck)?”

He replied: “Knowing I was going to be late initially was causing me some concern.

“I don’t like to fail the teams that I work with, even simply by being late.

“Initially I felt very frustrated and then obviously I researched, on trying to navigate a quicker route, I discovered the reason was that protesters were active on the M25, and then I changed my thinking.

“(I thought) I might as well use this to reflect again on why I am being delayed. That is what I chose to do.

“I sat and contemplated the reason that might have motivated the protesters to take that action.

“I thought about whether that action was productive and what it was doing. I took it as an opportunity to reflect on the fact I was in a traffic system sufficiently fragile, even normal disturbance would cause significant delay.

“I reflected on the fact that I was sweating quite profusely, it was a day after the UK had recorded its highest-ever temperature and two days previously the Government’s net zero plan had been declared illegal.

“I understood, I think, why protesters were taking their action.

“This led me to sympathise with the fact that I needed to be put in a position where I was forced to think about the gravity of the situation.

“Rather than sit and fret and sweat, I thought I would run through a process that would make the experience positive.”

Speaking outside court, Mr Packham said he believes Just Stop Oil and other protest movements “constantly need to change” tactics.

He added: “My message to the protesters as ever is let’s work together to think of creative, peaceful, non-violent means of communicating that message more effectively.

“It’s all right if you’ve got the motive but you’ve got to come up with a method that gets your message across, and the message is not getting across.”

He said he would work with the group if it comes up with “ideas that are peaceful and non-violent”.

He went on: “You’re not going to catch people’s eye unless you come up with imaginative, creative, new ideas.

“We should be looking at other aspects of culture, sport, music, all of the things that are integrated into our lives and using them and participants there to make sure we get our message across.”

Earlier on Wednesday, the defendant broke down in tears at points during cross-examination as she insisted she faced a “massive moral dilemma” by engaging in the protest.

The defendant, who has taken two years out of her studies, told the court she did not believe all lanes would end up closed and that she did not realise she was so close to Heathrow during the protest.

When asked whether she intended to cause “spectacular disruption”, she told the court she did not but soon “realised this was potentially a more effective protest than I thought it would be”.

The defendant denies one count of causing a public nuisance contrary to the Police, Crime, Sentencing and Courts Act 2022.

She does not dispute scaling the gantry but denies that it amounts to the charge.

The trial continues.