By Nick Assinder BBC News Online political correspondent

In 1999 the then education minister Estelle Morris said she would resign if the government failed to meet its targets on numeracy and literacy in 2002.

It hasn't, she hasn't and she has no intention of doing so.

Willetts given pledge

Nobody now denies she said it - in the Commons to her shadow at the time David Willetts.

Having said that, Ms Morris herself told a Commons committee just last year that she never said any such thing.

Still, she has now apparently refreshed her memory and accepts she did say it.

And no one in government denies that the department of education, which she now runs, has indeed missed those targets.

A Downing Street spokesman said the government had "come close" to meeting the specific targets she was referring to in 1999.

But he would not confirm that meant Ms Morris would come close to resigning even though she had refused to carry through her promise and then told the committee an untruth.

Good job

Apparently the important thing is all the good work she has done in the Department of Education since she became Education Secretary.

Rash promises are, it is suggested, trivia.

Mind you, Downing Street was careful not to answer a question about whether the prime minister believes Ms Morris to be an "honourable" woman.

Byers eventually went

Instead the prime minister's spokesman reeled out the usual statistics about what a good job she was doing.

That may well be the case. But that is not the issue.

The issue is the image of ministers in particular and the government in general, and whether voters can believe a word they say.

A level fiasco

It is no great surprise that the Tories are demanding Ms Morris' head - that is becoming an almost monthly event.

They list her "achievements" as the disastrous delays at the start of term when security checks had not been completed on teachers, the A level fiasco, and her failed attempt to intervene in the expulsion of two boys who threatened to kill their teacher.

She also came under fire for her remarks that there were certain comprehensives she would not touch "with a bargepole".

That, of course, may have been a Blunkett-esque attempt to chime with ordinary voters. If it was it backfired.

Drip, drip

And the new row came conveniently on the day the education secretary was facing more flak for allegedly trying to "fix" teacher shortages by handing more responsibility over to assistants.

The Tories are becoming used to the idea of demanding a minister's sacking and having their calls ridiculed by Downing Street.

But they do believe the drip, drip tactic can ultimately prove fatal. Just ask Stephen Byers.

The Tories claim she has been caught red handed.

And they believe that Ms Morris is rapidly approaching the point where she becomes an embarrassment to the prime minister.

She may not be in Byers territory yet, but she may not be far from it.