Unions and authorities were unable to predict as The TES went to press how many schools would be affected by the action on Tuesday by the National Union of Teachers and National Association of Schoolmasters Union of Women Teachers.

The unions are calling for an increase in London living allowances to pound;6,000 for inner London, pound;4,500 for outer London, and pound;2,500 for fringe areas. The change would put teachers on a par with police officers.

A previous one-day strike by the NUT in March failed to persuade ministers, even though it caused the full or partial closure of more than 1,500 schools.

The Association of Teachers and Lecturers is not taking part, after a ballot earlier this month in which 56 per cent of members voted against the strike.

At least 6,000 teachers are expected to join a protest march on Tuesday, which is due to start at Lincoln’s Inn Fields in central London and finish at The Oval cricket ground in Kennington.