In the 30 years since schools began to matter in politics, prime ministers have always interfered in education. Margaret Thatcher insisted on more facts in history, more maths and grammar and less of pretty much everything else. Sometimes her influence was benign - she was right about the overcrowded national curriculum. Sometimes it wasn’t. The same is true of Tony Blair. His commitment to schools has pulled more taxpayers’ money into education and given the drive for improvement a new sense of purpose. But sometimes his weakness for a wheeze to keep the punters and the newspapers happy gets the better of him.

It happened last week when, interviewed by the News of the World which had been running a drugs campaign, Mr Blair promised new powers for teachers to carry out random drug tests and to introduce sniffer dogs in schools. New guidance on drugs would be sent out to schools “next month”, he said.

The real story was rather different. The guidance does say that headteachers are entitled to use drug testing and sniffer dogs to look for drugs, but it goes on to warn them to take great care if they choose to do so. Appendix 10 of the advice, which seems to have escaped Mr Blair’s attention, offers half a dozen reasons why both measures may be problematic. Schools are asked to consider carefully whether “such action is consistent with the pastoral responsibility of a school to create a supportive environment”, whether it is “culturally insensitive” because dogs are considered unclean by Muslims and Buddhists, whether procedures are in place to remove pupils whose parents refuse consent, and so on. It does not sound much like the go ahead for widespread random testing. And this eminently sane guidance was not about to go out - it had already been dispatched.

The vast majority of heads will exercise their customary discretion in dealing with drug-taking pupils whatever the Prime Minister says, so why should we bother about a handful of misleading headlines?

I think we should. Voters may not notice, but heads and teachers observe that their political leaders are saying one thing and doing another. Mr Blair is also bolstering the dangerous notion that schools are the places to sort out social ills. Hard on the heels of the drugs pronouncement come new powers for heads to fine truants’ parents, turning them at a stroke into traffic wardens, magistrates and detective inspectors. Even if heads ignore them, the feeling grows that ministers are loading yet another burden on to hard-pressed schools with little regard for the complexities of classroom life.

It all adds to the sense that stunts are more important than “delivery”.

Yet the Government’s record on delivery in schools is perfectly respectable. Primary standards in maths and English are higher than ever, buildings are going up apace, more teachers are being recruited and thousands more three and four-year-olds are receiving nursery education, the key to narrowing the gap between the haves and have-nots. When Labour came to power, it was easy to sympathise with their need to provide the media with a wheeze a week to prove that something was happening. Now that there are real achievements to boast about, why resort to spin?