James Mee, 37, was pulled onto the platform at Canning Tube station and kicked by enraged passengers during the morning rush-hour on October 17, 2019.
Mee, an accounts administrator, and former Buddhist teacher Mark Ovland, 38, used a telescopic ladder to climb onto the train, jurors heard.
They unfurled a banner saying ‘business as usual=death’ while a public announcement told the crowd, which had gathered below the activists, to evacuate, Inner London Crown Court heard.
Edmund Blackman, prosecuting, said the pair were only on top of the train for 20 minutes but 48,000 people had their morning commutes affected.
XR activists Mark Ovland (left) and James Mee (right) used a telescopic ladder to climb onto a London Tube train
‘The attitude of the crowd and some of the public who were inconvenienced were angry and hostile and things on the platform got very ugly.
‘People were reaching up, trying to pull the people and the banner off the train, throwing things, coffee, coins, verbally jeering.’
TfL staff asked Mee and Ovland to come down but they refused.
‘A lot of people had their camera phones out, recording what was going on,’ said Mr Blackman.
‘One of the people who was recording seems to have been there by arrangement, involved in Extinction Rebellion, recording what was going on for, presumably, publicity purposes.
‘The crowd turned on him when they realised who he was and he was assaulted by members of the public on the platform.’
One passenger grabbed Mee and pulled him down to the platform where he was surrounded and kicked.
Another passenger climbed on top of the train and advanced towards Ovland.
‘Mr Ovland was part pushed off the train, part slid down of his own volition, realising that he might be thrown off or dragged down,’ said Mr Blackman.
After their arrest the two protestors refused to answer police questions but Ovland’s solicitor read out a prepared statement.
It said: ‘Today I was taking part in a demonstration to highlight the urgent issue of climate breakdown.
‘Business and government are not taking it seriously, as required, therefore I have no option but to do something before it is too late.
‘It is my moral and civic duty to bring the issue to the public’s attention…’
They were on top of the train for 20 minutes, the court heard.
‘Ten trains were cancelled,’ said Mr Blackman.
‘The train immediately before that was stuck between platforms and there were severe delays for 43 minutes.
‘TfL estimates that 48,000 people had their journeys affected by the actions of these two defendants.’
Mr Blackman told the jury: ‘This evidence is very unlikely to be disputed by the defence and therefore you may wonder to yourself what you are doing here.
‘The answer is this. As far as the defendants are concerned their actions that day were a proper exercise of their democratic right to protest, as we all have.
‘The prosecution say that was not a proper exercise and therefore they are guilty of a criminal offence.’
Mee, of Filton, Bristol, and Ovland, of Keinton Mandeville, Somerset, deny obstructing engines or carriages on railways under the Malicious Damages Act 1861.
The trial continues.