But the polls are also revealing glaring inconsistencies in the responses, and understandable gaps in people's understanding of words like "selection", "comprehensive", "choice", "grammar" and "grant-maintained". In general, voters believe strongly in comprehensives, but feel that a mother should put her own children first.
The latest Independent Communications and Marketing poll, published in the Guardian on Wednesday, asked a random sample of 1,200 adults whether Ms Harman was right or wrong, given that Labour opposes selection. Only 38 per cent thought she was wrong, 50 per cent supported her, and 12 per cent were undecided. Support for Ms Harman was strongest among Labour voters - 62 per cent felt she should not resign from the front bench. But, paradoxically, most of the sample said Labour politicians should send their children to comprehensives.
Respondents were also asked to choose between a system in which "all schools take a mixture of abilities" and one in which "some schools take only high ability and others take only low ability" - thus ruling out any confusion over the meaning of "grammar" and "comprehensive". Of the total, 65 per cent opted for comprehensives, as, surprisingly, did half the Tory voters.
One of the most interesting findings of the latest poll is that Labour voters make no distinction between council run and grant-maintained comprehensives, suggesting that the controversy over Mr Blair's choice of the London Oratory for his own son is a dead issue as far as the wider party is concerned.
The results of the Guardian poll tally with some of the conclusions of a poll conducted by the Association of Teachers and Lecturers two weeks ago which found that the strongest support for grammar schools comes from pensioners. The 18-24s, for whom education would be a recent memory, are the strongest advocates of comprehensives - 80 per cent favoured them over all other forms of school. The ATL's poll also found that voters in the lowest socio-economic group (DE) were most enthusiastic about the 11-plus, but this was not confirmed by the ICM poll - only 23 per cent of DEs preferred selective education, compared with 35 per cent of ABs.
Another ICM poll conducted for the Daily Mail last week found that 74 per cent supported Harman's decision "as a mother", while only 38 per cent backed it "as a Labour politician" - which probably proves little beyond the power of emotive language to blur issues of principle, or that opinion poll results will always vary widely according to how questions are phrased and how they are understood.