A trial of Extinction Rebellion protesters has collapsed after what a judge described as an “abject failure” by the Crown Prosecution Service.

Five climate activists were accused of gluing themselves to the concourse between London City Airport and its DLR station in October, and were due to go on trial at City of London Magistrates’ Court on Tuesday.

But the charges were dismissed after a police officer who was due to be a prosecution witness was not given enough notice about the date of the trial and had booked time off.

Deputy District Judge Vincent McDade said: “There has been an abject failure by the Crown Prosecution Service to ensure that this case has been properly managed.”

He said the absent police officer was required from the outset.

“Had the CPS acted efficiently and warned the witness as soon as possible after the case management hearing on November 7 this matter would proceed today with that witness giving live evidence,” he said.

The judge said the officer – who made the arrests – was a “vital witness to establish the lawfulness or otherwise of the arrests”.

An Extinction Rebellion protest at London City Airport
An Extinction Rebellion protest at London City Airport (Kirsty O’Connor/PA)

He said he had “no option but to dismiss all matters against all defendants”.

The five defendants who faced a charge of aggravated trespass were Claudia Fisher, 57, from Brighton, Phoebe Valentine, 23, from Brighton, David Lambert, 60, from Gloucestershire, Senan Clifford, 59, from Gloucestershire, and John Burrage, also known as Ben Bont, 42, from West Wales.

Former chief government scientist Professor Sir David King had been prepared to give evidence at the trial.

Speaking outside the court before he took his seat in the public gallery, he said climate change is “the most important issue humanity has ever had to face up to”.

Sir David King (back left), with Claudia Fisher, Senan Clifford, Ben Bont, David Lambert and Phoebe Valentine
Sir David King (back left), with Claudia Fisher, Senan Clifford, Ben Bont, David Lambert and Phoebe Valentine (Jonathan Brady/PA)

Afterwards he said the five got off on a technicality, but added: “On the other hand, the judge was relatively sympathetic, I thought.”

Earlier Sir David had said climate change requires “leadership from the very top” and described Brexit as a “distraction”.

He told the PA news agency: “What we are talking about is the most important issue humanity has ever had to face up to. And when I say humanity, I mean all of us. We’re all in this boat together.

“Whatever we do over the next 10 years on climate change, actions that we do, will determine the future of humanity for the next 10,000 years.

Sir David King arrives at City of London Magistrates’ Court
Sir David King arrives at City of London Magistrates’ Court (Jonathan Brady/PA)

“What we have got now is a very short timeline to get ourselves out of this mess.

“And yet the public have been barely aware of it. And the reason is quite simple.

“Initially, during the Blair and Brown period, it was very much in the headlines and I was on television and radio very frequently. But with the Cameron government it was a concern about slippage to Ukip and this was not an issue that was felt to be relevant for the main theme of the day.

“And so it was taken off the front pages. I wasn’t allowed on television and radio at that time. The result is that the public don’t even know what good things the British Government are doing.

“Everyone thinks the British Government have been doing nothing. It’s not true. Without Britain we would not have had the Paris Agreement. No government did as much as we did to achieve that.

“However, no government, including ours, is doing enough today. So what we need is much more action, much more clarity on the action that is needed, and we need it with a public voice.

“And that’s what Greta Thunberg and Extinction Rebellion have done. They’ve put it back on the front pages.”

He spoke about the importance of leadership, and said: “Boris Johnson is perfectly capable of stepping into that role but of course he has to deal with this thing called Brexit in the meantime.

“So what we have is a distraction from this enormous challenge.

“I’m afraid for future generations. I’m afraid for my children and their children, my grandchildren.

“I’m afraid because we haven’t been taking the actions that the science has been telling us to take for a very long time.”

He described the actions of the Extinction Rebellion activists as a “brave attempt” to get the “critically important” issue to the forefront.

After the charges were dismissed, Ms Fisher told PA: “That did not go how I expected. It was a complete surprise.”

Asked if she plans to get involved in future protests, she said: “Absolutely. Absolutely. This movement is going bigger and bigger. It’s unstoppable.”