Yesterday, it was simple arithmetic that caused blushes in the Blair household when Cherie gave a 10-year-old the wrong answer during the presentation of Tony's big idea on homework.
As political gaffes go, it was a mild one quickly corrected by the Labour leader and handled smoothly and with great humour by a slick husband-and- wife team.
But it was an illustration of the extent to which a message - in this case the recruitment of Premiership football teams to encourage children to do their homework - can be lost in a growing media maelstrom hungry for splits, cock-ups, injudicious asides and simple errors.
The Blairs were at Hillsborough, the home of Sheffield Wednesday FC, to launch the homework scheme under which four Premiership clubs, supported by private and public finance, would encourage literacy in problem children. Mr Blair was wired up for a satellite link-up with David Blunkett, the party's education spokesman, who was at Chelsea FC, one of the four clubs.
But first he hovered over 10 children aged from 10 to 13 who sat shivering, doing homework for the benefit of cameras, in the middle of the pitch.
"You'll need a rubber for that, it's wrong," he corrected Tom Lane, 10, from Brookhouse School in nearby Beighton. Unfortunately for the Labour leader, the lad pointed at Mrs Blair, who uses her maiden name, Booth, in her profession as a barrister, and said: "But she told me ..."
"Gosh," said Mr Blair, laughing at his wife. "And you with all those brains, too."
"Oh, all right, show off," she replied. "I'll never hear the end of this, will I?"
Indeed not. Already news desks across the country were being alerted to the gaffe. Mark Covell, Labour's regional press officer, said the question was from a year-six homework paper. "It said something like 'If you had so much money to take to the fairground, how many rides could you go on?'" he said. "Tom wanted to go on the big wheel. Cherie gave him the wrong answer and Tony quickly corrected him."
But too late. It had already become the highlight of a rather dull day on the election stump.
A plan to create a government co-ordinator to tackle the country's drugs crisis will be announced by Tony Blair today.
The Labour leader has been persuaded that concerted action is needed to curb the drugs problem. During a visit to Aberdeen today he will say that, if elected, he will appoint an overlord to take on the drugs barons; someone with the power to call in the police, education authorities, the Prison Service and any other body facing a drugs problem, to co-ordinate action.
Labour said last night that the number of people convicted of drug offences in the United Kingdom had more than trebled over the last decade; up from 26,958 in 1985 to 93,631 in 1995.