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 shadow education secretary, 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 one of them, 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, alright, show off," she replied. "I'll never hear the end of this, will I?"
Indeed not. Already newsdesks 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. Earlier, the Blairs had visited the Peak National Park in Derbyshire to drum up support for Tom Levitt, the candidate for High Peak, number 53 on Labour's list of 56 seats it must take from the Tories if it is to seize power.
No gaffes there as the couple joined children at nature tables in the mud and drizzle. But there was a high point when one Labour media apparatchik dangerously hopped over a cattle grid and ran to the assembled press shouting: "Look, look! They've found a frog!"
With six more weeks to go, questions remain over whether, with such tension in the air, the candidates will crack.Reuse content