Mr Johnson has tried to avoid disclosing his views on individual songs, but conceded that pupils could belt out "Sing if you're glad to be gay", by Tom Robinson. "Onward Christian Soldiers" was less likely to make the cut, he said.
But the most alarming contributions are likely to come from the Prime Minister, who is said to have identified Robin Gibb, his holiday host and Bee Gee singer, as "a hero of mine".
Mr Blair's iPod also contains Christina Aguilera. Nonetheless there is one singer at whom the Prime Minister draws the line.
Last week at Downing Street, an official from the National College for School Leadership told him there were cracks in the system for developing future heads, but that, in the words of moody Canadian songwriter Leonard Cohen, "there's a crack in everything - that's how the light gets in".
The Prime Minister baulked - well, the Government is spending pound;10 million encouraging children to sing. "Couldn't you have been more optimistic than Leonard Cohen?" Mr Blair said.