After successfully wooing three teaching union conferences, she foundered when parents forced her to justify Government cutbacks and the decision not to fund the entire 2.7 per cent pay rise.
Her 45 minute speech was listened to politely but received only lukewarm applause from the 200-strong audience.
But the minister's ususally cool, calm exterior appeared to crack when a mother asked how a £40,000 budget cut at her primary school, which could lead to two teacher redundancies and possible class sizes of 45, could be justified.
Mrs Julia Evans, clearly unhappy with an answer about general figures, insisted: "I am sorry but I do not think you have answered my question," amid loud applause.
The Education Secretary apologised and attempted to redress the issue. But when she suggested that parents should ask what balance a county council might be holding back and question the way the school was managed, hissing and laughter broke out.
Mrs Shephard appealed for parents and governors to persuade "sensible teachers" not to take industrial action.