But Sue Sayles, outgoing president of the National Association of Head Teachers, could not resist it when she introduced the new schools standards minister to delegates: "Yes, I thought the same as you - a Year 8 in a suit."
Aged 36, and a minister after just one year in Parliament, Mr Miliband is young, but standing before heads with centuries of experience between them, it was hard to believe he was the new boy.
His polished speech wom sustained applause. It was a charm offensive, playing up his own schooling at Haverstock comprehensive in north London, and winning more support than expected.
"I am here because of state education. My primary school failed to convince me that there was anything more important than football, but it did prove to me that there were other things to read about. My school may not have got me close to mastering physics A-level but it gave me a sense of inquiry and got me into university. My philosophy is clear: my job is to help you ensure that all children get the opportunities they deserve."
His passion and commitment shone through and it was clear that after seven years as Tony Blair's head of policy, he knew not only what buttons to press but how to get them to do what he wanted.
Rumour has it that the spell-checkers on DFES computers come up with Mr Militant every time they hit his name. Militant only, it would appear, in his zest for reform. The modernising streak runs deep. At Oxford, he was campaign organiser for an independent reform candidate who beat one Stephen Twigg, the official Labour candidate, for the Oxford University Union in 1987. Mr Twigg, MP for Enfield Southgate, joined Mr Miliband as a new minister at the DFES on May 29.
David Hart, NAHT general secretary, said: "It matters not a damn if he's a Year 8 in a suit or a minister in his 60s, it is the message that is important. If he can deliver at 36 it's a darned sight better than someone who can't at 56."