Large parts of Britain witnessed by a day-long strike on Thursday called by four major unions that led thousands of state school being closed and air passengers are Heathrow and elsewhere delayed at immigration desks.

As a show of defiance against the striking teachers, Prime Minister David Cameron dropped his two eldest children Nancy, 7, and Arthur, 5, to school in west London this morning.

However, deputy prime minister Nick Clegg preferred not to take his children to their school which was closed.

Elsewhere, nearly 12,000 state-run schools were officially closed. The strike has been called against pension reforms and spending cuts that have led to thousands of job losses.

The four unions on strike are the Public and Commercial Services Union, Universities and College Union, Association of Teachers and Lecturers and the National Union of Teachers.

At Heathrow airport, passengers said they were delayed at the immigration desk but “not excessively delayed”.

In a heated discussion on BBC Radio this morning, cabinet office minister Francis Maude said: “All the early indications I’m getting from airports and ports are that fewer (union) members are heeding inflamed calls for action, more are turning up for work and we are maintaining a much better service than we expected to be able to.”

He said the strike was premature given that negotiations on pensions were ongoing, and noted that Unison, the biggest public sector union with 1.3 million members, had opted to keep talking, although it may strike later this year.

He added: “You cannot continue to have more and more people in retirement being supported by fewer and fewer people in work. Long-term reform is needed.”

Mark Serwotka, general secretary of the PCS, said his members were left with no choice but to take action as the government was not prepared to “compromise on any of the central issues of the strike. While they are talking, they are not negotiating.”

Kevin Courtney, deputy general secretary of the NUT, said early indications suggested “large numbers” of schools were closed or partially affected by the action.

He said: “We realise that’s very disruptive for parents and we do regret that. We had hoped to reach a settlement before the industrial action, but the government isn’t serious about talks.”

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