The difficulty, said the chap from the Society of Podiatrists, was with the motion of the foot. He was explaining to gathered unionists why schools should have to provide pupils with regular foot health screenings.
But he could have been referring to the deft motion with which the previous speaker, one Alistair Darling, had inserted his foot in his mouth. The Chancellor had just finished boasting about how he had increased the pay of teachers and other public sector workers. Contrast that with the Conservatives, he said, under whose leadership child poverty had trebled and teachers had shivered in Victorian classrooms.
But the claim that child poverty had trebled under the Tories was grossly inflated.
And the claim that public sector pay had increased by 39 per cent since 2000 was greeted with derisory snorts. Indeed, the Chancellor might have expected a more hostile reaction than snorts. Heckling, maybe. Howls of outrage.
But perhaps the union leaders knew that their credibility, like Mr Darling's, was tarnished.
They too suffer foot-in-mouth disease. All year, they have talked up mass walkouts that would affect every school and hospital in England - only to discover that their members show little appetite for returning to the rusty barricades of the 1980s.
NASUWT leadership is reduced to pretending that local action over teachers' workload is actually part of a grand plan of co-ordinated national strikes.
National Union of Teachers members may walk out of the classroom in November, joined by a few classroom assistants. But two out of three teachers will stay in school, loath to anger parents.
The Chancellor and his ministerial colleagues will rightly conclude they have nothing to fear from unions that cannot agree among themselves.