A British man conceived a son with an African woman in the "usual way" - with his wife's approval, a family court judge has been told.
The man's wife was unable to give birth because of medical problems and the couple made a €2,700 (£2,000) arrangement with the woman, who lived in Germany, Mrs Justice Pauffley heard.
She told her husband she had met the African woman who was a "nice girl" and was "willing to have a baby for them".
Less than two months after the meeting, the man travelled to Germany and the little boy - now about 18 months old - was conceived.
The wife said she had "tried to black out" the fact that her husband and the African woman "would be having sex".
Detail of the case has emerged in a ruling by Mrs Justice Pauffley following a private hearing in the Family Division of the High Court in London.
The judge was asked to make decisions after the woman and the couple fell out over the terms of their arrangement.
She described the dispute as "quite extraordinary".
The judge said no one involved could be identified, but she said the couple lived in London and the boy was born in Germany in the autumn of 2013.
Mrs Justice Pauffley said the woman and the couple had been in dispute over where the little boy would live.
Barrister Deirdre Fottrell QC, for the woman, said the arrangement had been that the boy would live with her client but see her father regularly.
The woman said she had "rights of custody" under German law - and argued that decisions about the boy should be made by a judge in Germany.
Barristers Andrew Norton and Marlene Cayoun, for the British man, said the agreement had been that the boy would live with him and his wife in England and see his biological mother during holidays.
They said the little boy was a British citizen.
Mrs Justice Pauffley ruled in favour of the British man. She concluded that the woman had given "clear and unequivocal consent" to the little boy leaving Germany for England and said disagreements should be resolved in an English, not a German, court.