“We did not want the impression that this was a report by a Conservative committee, unanimously made.”

Thus one of the Conservative MPs on the Select Committee on Education and Employment, speaking about the Tories’ reluctance to publish the highly critical report on nursery vouchers in its current form.

Tory members of the committee, led by Graham Riddick, MP for Colne Valley, battled hard to ensure that the final version of the report contained criticisms only of the practical working of the scheme, not of the principle of nursery vouchers. When they failed to secure the changes they wanted, two of them voted against publication and four abstained.

Mr Riddick, for instance, had tried and failed to have the section questioning whether vouchers would actually increase parental choice replaced by a bland statement welcoming the fact that vouchers had “resulted in places for pre-fives in educational settings”.

But all five Labour members and Don Foster, the Liberal Democrats’ education spokesman, voted in favour of publishing the report as it stood. All that remained to be decided was the timing and method.

Then a leak of the draft report to The Independent almost made that decision irrelevant - and probably gave the report more publicity than it would otherwise have had. “Tories scorn Major’s nursery revolution” ran the headline over the story. The “Tory-dominated committee” had found that “John Major’s flagship nursery scheme” was “unlikely to raise standards, increase parental choice, or even provide extra places for children”.

In vain did Tory MPs protest that the committee, equally balanced between Conservative and Opposition members, and with Tory chairman Sir Malcolm Thornton behaving as an impartial chairman, had had to operate largely by consensus. The damaging impression remained that Conservatives had damned their own scheme.

All sides professed to be shocked by the leak. All protested their innocence. Graham Riddick said it showed “how low the Opposition would stoop”; Don Foster said it would reduce the report’s impact and be of benefit only to spin-doctors; Labour condemned the leak but said it would say no more until the culprit was revealed. Sir Malcolm wrote to all committee members asking them to confirm in writing that they had not been involved.