Justin Welby has discovered his real father was not Gavin Welby, the former husband to his mother Jane Williams. 

Instead it has been revealed archbishop of Canterbury was born out of a brief affair between his mother and Winston Churchill's private secretary, Sir Anthony Montague Brown. Now re-married to Charles Williams, Welby's mother Jane Williams has issued the following statement:

Although, as has already been made public, Gavin Welby and I had a short and, sadly, dysfunctional marriage, neither of us ever doubted that we were the parents of our son Justin, who was born almost nine months to the day after our marriage in America on April 4, 1955. I still recall our joy at his arrival. So this DNA evidence with which I have now been presented proving that Gavin was not Justin's biological father, so many years after Gavin's death, has come as an almost unbelievable shock.

Naturally, my son has deserved an explanation and I have been as open as I can, given the passage of more than sixty years with all the lapses in memory that age entails, in giving it to him. But I accept that what would in normal circumstances be of interest only to those immediately concerned must now, because of my son's position in public life, be given wider circulation. So I write this in order that the matter be put to rest.

Gavin Welby, my ex-husband, was a very strong, possessive character. At the end of March 1955 he was bullying me to leave my job as personal secretary to the Prime Minister and run away with him and marry him in the United States where his divorce was being finalised. At the age of 25, as I was, the pressure became too great and in the end I found myself unable to resist.

One feature of this pressure is that I was already drinking heavily at times. Although I could then ensure that this did not affect my work, it was later to develop into serious alcoholism during the 1960s which only came to an end when I entered rehab in 1968. I have not drunk alcohol since.

Although my recollection of events is patchy, I now recognize that during the days leading up to my very sudden marriage, and fuelled by a large amount of alcohol on both sides, I went to bed with Anthony Montague Browne. It appears that the precautions taken at the time didn't work and my wonderful son was conceived as a result of this liaison.

After leaving my job and getting married, I didn't see Anthony again for a long time. After Gavin and I broke up in 1958 Anthony and I met occasionally but although he may have asked how Justin was, there was nothing that gave me any hint that he might have thought he was Justin's father.

My beloved husband Charles Williams and I have enjoyed a loving and stable marriage from 1975 to the present day. With that stability and love I have been able to blossom as never before. I have served on the Parole Board, as a magistrate, as a member of a Board of Visitors of a prison, as chair of a Howard League committee and as a deputy lieutenant for Greater London. Even at the age of 86 I lead an active life both in support of my husband and in my own right.

Furthermore, I have watched Justin, from an almost impossible childhood (Gavin was alcoholic as well), grow into what he is today, marry his beautiful wife Caroline in 1979 and see his children and now grandchildren grow up around them. As a family we are truly blessed. But none of this would have been possible without our firm Christian faith and a determination never to relinquish hope. God has given us so much and my gratitude knows no bounds.