Labelled "a strike" by the BBC, the Government called the sight of thousands of children skipping school plain "truancy".

Theresa May condemned it, with the Prime Minister's deputy official spokesman saying: “It is important to recognise that disruption increases teachers’ workloads and wastes lesson time that teachers have carefully prepared for.

“That time is crucial for young people precisely so that they can develop into top scientists, engineers and advocates that we need to tackle this problem."

Labour leader Jeremy Corbyn, saw it differently, saying it was "inspiring to see them making their voice heard". Pupils could be heard chanting his name throughout the day.

Business minister Claire Perry — siding with some Labour frontbenchers — told BBC Radio 4’s Today programme: “I suspect if this was happening 40 years ago, I would be out there too.

“I’m incredibly proud of the young people in the UK who are highly educated about this issue and feel very strongly – quite rightly – that we do need to take action because it’s their generation that will bear the consequences.”

Carolyn Fairbairn, the director general of the CBi, raised eyebrows by supporting the protest.

She told one of the protesters who was appearing on the BBC’s Politics Live it was “great” that the school children were “standing up for what you believe in” but she hoped it would not be every Friday.