Mr Trinder, chief economist for the Chartered Institute of Public Finance and Accountancy, believes the Government's reaction to the figure, which was released this week, will be to accept a pay rise of only 3 per cent for teachers.
The average earnings index is the last piece of the financial jigsaw for the School Teachers' Review Body which is preparing its report for publication at the end of the month. Mr Trinder said teachers' salaries were already under pressure because governors are not awarding discretionary payments: "Without these extra payments, teachers are slipping down the earnings league."
He said the Government should honour any award the review body recommends in order to recruit and retain staff. He warned that if analysts are correct in forecasting that private sector pay will rise by between 4.4 and 4.8 per cent this year, teachers will be left behind.
Teachers' unions warn that if this is the case, pay will be pushed to the top of the agenda at the Easter annual conferences. Eamonn O'Kane, deputy general secretary of the National Association of Schoolmasters Union of Women Teachers, said: "For the past two years we have been most concerned about conditions of service and workload, but if teachers only receive a 3 per cent rise this year it will provoke a sharp response from our members.
"The run up to an election usually concentrates the minds of politicians wonderfully - and I hope Gillian Shephard will take inspiration from Kenneth Clarke, her predecessor, who just before the last election, managed to find Pounds 60 million for teachers' pay."
The Teacher Training Agency has predicted staff shortages, particularly in the secondary sector. Anthea Millett, the TTA's chief executive, described her task to increase numbers of newly qualified teachers from 20,000 to 30,000 a year as "challenging".
* The Association of Metropolitan Authorities has written to school governors saying that the 4.5 per cent extra Mrs Shephard said is available for schools would mean making cuts in other hard-pressed council services. The letter says: "AMA-member local education authorities have shown repeatedly that education is a priority, but regrettably they may be forced to make cuts."