The poll, carried out for the National Union of Teachers by ICM Research, shows Labour with a towering 38-point lead over the Liberal Democrats, with the Conservatives trailing in third place on 15 per cent.

Labour, on 59 per cent, now outstrips the Conservatives by nearly four to one. The findings disclose deep dissatisfaction among teachers with government education policies, particularly the constant pace of change, excessive bureaucracy and political interference.

They also feel under acute pressure from increasing numbers of disruptive pupils, lack of preparation time and the new school inspection regime.

The poll reveals that the Conservatives are even less popular with the profession than among the general public, while Labour enjoys an 11-point bigger lead among teachers than among the electorate as a whole.

The Liberal Democrats also claim greater support among the profession, but their 21 per cent rating among teachers is three points lower than immediately before the 1992 election.

A separate poll of the general public puts Labour well ahead of its rivals on four key education policy issues. The poll of 957 voters carried out for the Association of Teachers and Lecturers by Harris shows they believe Labour is most likely to invest in education, with the Liberal Democrats coming second. The Conservatives trailed badly.

Almost half the electorate felt the Conservatives would do nothing to put more cash into education, improve job prospects for their children, get the best out of teachers or raise the quality of education.

According to the NUTICM poll, teachers’ top two demands for the next government are for smaller classes and more investment for schools. Labour’s support among teachers has strengthened even further since the last election when, according to a TESICM poll, 51 per cent said they would back the party. At that time, 24 per cent backed the Lib-Dems and 20 per cent, the Conservatives.

Support for the Liberal Democrats among teachers interviewed for the NUT poll was five per cent higher than among the general public - 21 per cent compared with 16 per cent. It was 15 per cent lower for the Conservativ es among teachers than among the general public, where ICM’s latest poll shows that 30 per cent of the voters would back the Government.

The first shift against the Tories came in 1987 when 46 per cent of teachers said they would vote Lib-Dem Alliance, while Labour had 28 per cent and the Conservatives 24 per cent.

In the 1983 election the Conservatives enjoyed the support of 44 per cent of teachers and Labour trailed two percentage points behind the Alliance, who had 28 per cent.

Education, not surprisingly, was the key policy area that influenced teachers in choosing a party, followed by health and law and order.

Just 62 per cent of teachers, however, said they would turn out to vote on May 1 - 8 per cent less than the general public.