Marriage is no longer seen as the foundation stone of family life by a majority of people in Britain, a major study of public opinion suggests.

The belief that couples should ideally get married before starting a family has effectively collapsed within a generation, according to the British Social Attitudes survey, the longest running and most authoritative barometer of public opinion in the UK.

Forty percent of children are now born outside marriage in Britain and marriage rates have plunged.

The survey showed that only a minority of people now view marriage as the starting point for bringing up children, with support for that view almost halving in less than 25 years, the Daily Telegraph reports.

The survey highlighted a series of significant changes in attitudes toward sex, politics, economics, and issues such as welfare and Britain’s relationship with Europe since it first began in the early 1980s.

But some of the most dramatic changes are in the area of family and relationships, with views once classed as permissive now becoming the norm.

Moral disapproval of matters such as sex outside marriage and homosexuality has fallen sharply since the 1980s, it shows.

However, disapproval of adultery is higher now than a generation ago.

The survey, conducted by NatCen, a social research group is based on detailed interviews with more than 3,000 people who were asked the same set of questions about life in Britain as the study has posed for three decades.

This year’s report, which charts how opinions have changed in that time, finds evidence that people have become increasingly individualistic.

While this is partly reflected in differing attitudes to issues such as the welfare state, it concludes that the biggest shift has been in moral matters.

Having turned their back on traditional moral standards and religious affiliation, people have become increasingly willing to “create their own moral codes” the report argues.

When asked how whether or not people who want to have children “ought to get married” seven out of 10 people agreed in 1989.

Last year only four out of 10 people agreed with the idea.

When responses from different age groups were compared, the study showed that younger people have a more relaxed attitude to marriage than older people.

But even then, the gap between the oldest and youngest generations on the question of marriage is half what it was 30 years ago.

Nevertheless Harry Benson, of the Marriage Foundation think-tank, predicted that while people had “lost confidence” in marriage, it is likely to stage a resurgence.

“What we’re seeing is a response to the doubling of family breakdown during the last thirty years,” he said.

“We value commitment and faithfulness ever more. But we have lost confidence in marriage.

“The tide will turn when we realise once more that marriage is the best way to achieve both.”

The study showed that in some areas or morality, attitudes have become less permissive rather than more.

The latest survey found that 63 per cent of people think that adultery is “always wrong” compared with only 58 per cent in 1984.