The former archbishop of Canterbury Rowan Williams has led a group of 70 public figures, politicians and academics who today argue in a letter that the 50 per cent cap for faith schools on admissions on the basis of religion must not be lifted.

The signatories have waded into a highly sensitive issue that cuts across politics and religious affairs, with campaigners rejecting Catholic and Muslim pleas for more freedom, warning instead against exclusive and closed religious communities of pupils.

The letter signed by Dr Williams, Andrew Copson, the chief executive of Humanists UK and Richard Dawkins among others, comes amid speculation that the new education secretary, Damian Hinds, is set to follow through on a controversial Conservative change of policy announced in November 2016 paving the way for lifting the cap, which was introduced in 2010.

The letter to the Daily Telegraph points out that opinion polls showed that 80 per cent of the public opposed a change in policy. It says that scrapping the cap would be 'deleterious to social cohesion and respect' and 'allows schools to label children at the start of their lives with certain beliefs and then divide them up on that basis'.

The letter, also signed by Caroline Lucas, the co-leader of the Green Party and Baroness Joan Bakewell, states: 'The Government rightly identifies the promotion of mutual understanding and tolerance for those of different religions and beliefs as one of the most important roles for schools. As we are all aware, children are blind to the differences and immune to the prejudices that so often divide society. The duty of the education system... should not be to highlight and entrench such differences.'

The Catholic Church is strongly opposed to the cap and has said that it would not establish any new schools as long as it was in place, arguing it has a duty to educate Catholics.

But the Church of England said that the cap did not affect its work. Nigel Genders, its chief education officer, said: 'Neither the removal nor the retention of the faith cap will impact on our existing schools or any new ones we open.'