Euan was just doing what comes naturally

It happens to every parent of teenage boys. But as Tony Blair's press spokesman, Alastair Campbell, told reporters today, not every teenager who goes out and "ends up a lot worse for wear" ends up all over the news.

Euan Blair had just finished his GCSEs at the Oratory School in West London and went out with friends to celebrate in and around London's Leicester Square - half a mile from the boy's famous Downing Street home.

As midnight approached, Mr Blair, still working on his government's health and spending plans, began to fret. Euan had stayed out late before, but had "never been brought home by the Special Branch".

The teenager had been found lying on the pavement and had been vomiting. An ambulance had been called but not needed. Euan, still only 16 and legally too young to buy drink, was taken to Charing Cross police station where he gave a false name - Euan John, a false age - 18, and a false address, his old one.

It did not take long for the police to find the truth and ring No 10. Euan spent some time in the cells before being collected. He will have to go back to the police station - with both parents - to hear if he will be charged for being drunk and incapable or - much more likely - cautioned.

What the boys drank and where they drank it was not divulged. No 10 was quick to accept that under-age drinking made Euan a legitimate target for media attention, but almost as quick to stress that the family still deserves it privacy.

Mr and Mrs Blair are strict parents who practise what they often seem to preach to the electorate: parental responsibility, individual duty, the belief that raising children properly is one of the most important civic duties we all have.

That is not surprising. The prime minister was raised in a high-achieving, upwardly mobile family. Cherie Booth QC fought her way out of poverty in Liverpool, raised by a tough mother abandoned by her wayward and boozy husband, the actor Tony Booth.

No wonder they are strict about drink. But Euan is the eldest of their four children. The Blairs must be preoccupied with baby Leo. The natural teenage desire to kick over the traces met its inevitable opportunity. There were hints that he has had a few scrapes before.

How will voters react? Some glee that a politician who urged on-the-spot fines for drunken hooligans only last weekend has egg on his face? Almost certainly, but it will be mixed with sympathy, especially for young Euan.

Growing up is hard enough for any teenager, and far more so in a goldfish bowl, as Prince William can testify. Everyone over 40 in Britain remembers his father - now Prince of Wales - going into a pub at 14 and innocently ordering a cherry brandy.

Plenty of politicians' children have rebelled against family pressures and sometimes against neglect or excessive discipline. Occasionally a case ends in tragedy - as happened to cabinet office minister, Ian McCartney, when his son died of a drug overdose.

Home secretary Jack Straw was luckier. When his 17-year-old son, William, now a student at Oxford, was exposed selling small quantities of cannabis to a pretty Fleet Street reporter his father marched him to the local police station.

Such incidents are routine stuff nowadays and Euan's offence was far more trivial. Mr Campbell said the boy's parents wanted him to have "as normal an upbringing as possible". On Wednesday night's evidence they seem to be doing pretty normally.