Labour and Conservative MPs are often portrayed by critics of the party system as like Tweedledum and Tweedledee: essentially alike for all the sound and fury of their battle. But this is a false impression. A striking new survey by Populus about the attitudes of MPs reveals not only deep underlying disagreements between Labour and Conservative MPs on key social values, but also big divisions within the Tory party. David Cameron has failed to persuade a large number of his own backbenchers to accept his liberal views on morality and race.

The survey of 128 MPs was conducted by Populus between May 9 and June 1 and the sample was weighted to reflect the balance of parties within the Commons, so 70 Labour MPs were included, 39 Tories, 13 Lib Dems and six others. Perhaps unexpectedly, Labour turns out to be more cohesive than the Tories. On every statement apart from one, 83 per cent or more of Labour MPs agree (the exception being whether Britain is a united country, where there is a 59 to 41 per cent split).

By contrast, on several key questions Tory MPs are deeply divided. For instance, against the view of Mr Cameron, just 46 per cent of Tory MPs agree that gay couples should have the same rights as heterosexual couples, with 54 per cent disagreeing. For comparison, 83 per cent of Labour MPs and 92 per cent of Lib Dems agree.

Similarly, there is a 52 to 48 per cent split among Tories on whether “the diverse mix of races, cultures and religions now found in our society has improved Britain”. By contrast, 92 per cent of Labour MPs agree, as do all Lib Dems surveyed. And while Labour MPs are virtually unanimous (94 per cent) in agreeing that “one of the things that would most improve life in Britain today is people being more tolerant of different ethnic groups and cultures”, that is the view of only 67 per cent of Tory MPs.

The survey also shows that if you scratch beneath the surface, MPs from the two main parties have very different views on public services. Roughly nine out of ten Labour and Lib Dem MPs agree that “if we were starting with a blank piece of paper and designing a health system for scratch, we would still create something very much like the NHS”, but only two fifths of Conservative members agree.

Private schools appear as a sharp dividing line. More than four fifths of Labour MPs (85 per cent) believe “it would be better for the country if everyone who sends their children to private schools chose to send them to state schools instead”, a view backed by only 7 per cent of Tory MPs.

Some divisions are more about which party is in power. So, while 98 per cent of Labour MPs and 85 per cent of Lib Dems agree that “Britain is a better country to live in now than it was 20 years ago”, only 41 per cent of Tories agree. Similarly, about three fifths of Labour and Lib Dem MPs agree that Britain is a united country, but only about a fifth of Tory MPs do.

On most issues, Liberal Democrat MPs are quite close to Labour and a long way away from the Tories, underlining the obstacles in the way of creating a Conservative-Lib Dem coalition if there were a hung Parliament.

Finally, the survey reveals a characteristic British touch of complacency. The one statement about which there is a high degree of agreement across party lines is “Britain is a tolerant country”, which is backed by 91 per cent of Labour MPs and 85 per cent of Tories. Tolerant maybe, but certainly not in agreement about basic political values.

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