Tory MP Suella Fernandes and audience members on Question Time rounded up on the Green Party co-leader as he also said Brexit voters had been “misled”.
Host David Dimbleby also got in on the action as he said Mr Bartley “assumed” to know why people voted for the UK to exit the European Union (EU).
Speaking on Question Time on the BBC, Mr Bartley said: “I think we’ve seen a right-wing coup in this country already with this Government now pushing forward an extreme Brexit.
“Ukip said jump and the Government said how high and I’m really worried.
Jonathan Bartley said voters did not vote for a country that was "less prosperous"
I think the wheels are already coming off the Brexit bus
“We’re a week into Brexit and triggering Brexit and I think the wheels are already coming off the Brexit bus.
“They didn’t vote for a country that was less prosperous.”
But Dimbleby questioned the co-leader’s assumption and suggested many “knew what they were doing”.
He said: “You’re assuming people voted the way they did, you didn’t like the way they voted so you assume the worst motives.
Brexit debate in pictures: Farage blasted by EU boss Wed, April 5, 2017
The debate in the European Parliament in Strasbourg will focus on key issues of the Brexit talks including reciprocal rights for EU citizens, the peace process in Northern Ireland and trade
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Nigel Farage gestures during speeches at the European Parliament in Strasbourg, eastern France
“Maybe people voted the way they did because they wanted to vote that way and knew what they were doing.”
Mr Bartley responded by putting the blame on the referendum campaigns.
“I think people both on the Remain side and the Leave side voted in good faith, absolutely,” he said. “I think there was a terrible referendum campaign and people were misled.
This prompted Ms Fernandes to angrily step in and tell Mr Bartley to be “more positive”.
To cheers from the audience, the MP for Fareham said: “Stop talking down our country. Stop patronising the voters and telling the how they voted. Let’s be more positive.”