The Archbishop of Canterbury was visiting a playgroup when he received test results on his iPhone confirming that his biological father was not the man he had previously thought.

Rev Justin Welby announced that his father was not Gavin Welby but the late Sir Anthony Montague Browne - Sir Winston Churchill's last private secretary.

His mother, Lady William, then Jane Portal, was Sir Anthony's colleague when she worked as the Prime Minister's personal secretary.

The confirmation came on the Wednesday before Easter when the Archbishop received the results of a paternity test that compared a DNA swab from his mouth with hair from Sir Anthony's hairbrush, he told The Telegraph.

In an interview with the newspaper's former editor Charles Moore, who was told about the paternity doubt by Sir Anthony's widow Shelagh Montague Browne, the Archbishop said he had originally thought the suggestion was "beyond the realm of reasonable belief".

The Archbishop said he had originally thought the suggestion was "beyond the realm of reasonable belief"

Lady Montague Browne said she was aware that her husband may have had another child and that once the Archbishop started appearing on television she saw the resemblance between them.

By early 2013, just before the then Bishop of Durham took up his post as Archbishop of Canterbury, Sir Anthony was in a care home but, via his wife's son, asked the Archbishop to visit him, the Telegraph reported.

The Archbishop agreed to arrange a time to visit and planned to arrange a visit when,"all the hooha of moving had died down", he said.

But when he did try to make the plans, it was too late. Sir Anthony had died on April 1.

Earlier this year, when he received the results of the paternity test on his mobile phone while visiting a playgroup in Sittingbourne, Kent, Mr Welby said he walked towards a window, "anxious to learn the news".

The DNA test showed the pair matched on all 15 genetic markers and a letter from the geneticist Professor Sir John Burn said that the probability they were father and son was 99.9779%

On Maundy Thursday he phoned his mother and said: "It was difficult. She was very shocked. But my mother is extraordinary. She always looks reality straight in the face."

But Mr Welby insisted that he was not upset and said that, if his newly discovered half-sister Jane Hoare-Temple was keen, he would like to meet her and her son, his half-nephew.