The Grant-Maintained Schools Foundation claimed alternative arrangements were likely to provide a better service. It said research had revealed that up to 89 per cent of GM schools which had stopped using their former LEA to provide services believed that there had been major improvements.

In addition, the foundation said the proportion of schools with improved services was far greater among those which now used alternative providers rather than LEAs.

Its claims are based on the results of the annual survey of GM schools which was conducted by Research International. According to the GMSF, 71 per cent of schools using non-LEA payroll services reported an improvement. The comparable figure for schools using LEA service was 30 per cent.

For catering, it said 79 per cent of schools who had sought alternative help reported an improvement in contrast to 43 per cent of those remaining with their former LEA.

In a letter to the Grant-Maintained Schools Advisory Committee, Sir Robert Balchin, chairman of the GMSF, urged heads and governors to look to other contractors, or LEAs, or do the work in-house.

He said any of the alternatives were likely to provide a better service. And he added: “By shoddy performance under contract, many LEAs still contrive to hold schools back even after they have gone GM. We would urge every GM school management team to review their LEA contracts if there has not been a significant improvement in the service they have received since opting out.”

Graham Lane, chair of the education committee of the Association of Metropolitan Authorities, said the call for GM schools to end contracts with local authorities was “futile whistling in the dark”.

He questioned the quality of the annual GM survey but said: “It is no more suspect that you would expect coming from an organisation whose main reason for existence is ending the links between schools and LEAs”.