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A super sperm donor may have fathered up to 1,000 children in a baby clinic he ran with his wife, it was revealed yesterday.

Bertold Wiesner and Mary Barton’s controversial clinic for high IQ donors helped women conceive more than 1,500 babies.

Now two men who discovered they are Wiesner’s biological sons claim to have found evidence he fathered hundreds of other children.

One of the men, London-based barrister David Gollancz, estimates Wiesner is responsible for 300-600 children.

But Canadian filmmaker Barry Stevens, believes the true number could be 1,000.

The Barton Clinic, set up in London in the 40s, was highly controversial because it used a small number of specially-selected highly intelligent men as donors.

The then Archbishop of Canterbury called the clinic’s activities “the work of Beelzebub” and called for it to be shut down.

One donor, neurochemist Derek Richter, was found to have fathered more than 100 of the babies.

But new DNA tests reveal that number was dwarfed by the achievements of Austrian-born biologist Wiesner.

Mr Stevens and Mr Gollancz were both conceived by artificial insemination at the clinic and the pair have produced research that they claim proves Wiesner made two-thirds of all donations.

DNA tests carried out in 2007 on 18 people conceived at the clinic between 1943 and 1962 showed 12 were Wiesner’s children.

Mr Gollancz said: “A conservative estimate is that he would have been making 20 donations a year.

"Using standard figures for the number of live births which result, I estimate he is responsible for 300 and 600 children.”

Mr Stevens believes it could be 1,000 – but even 600 would beat previous records. Allan Pacey, chairman of the British Fertility Society, said Mr Gollancz’s calculation was “plausible” adding that a healthy man could make up to 50 donations a year.

Last year it emerged an anonymous American donor had fathered 150 children.

Wiesner died in 1972 but Barton, who is also dead, previously said she limited the number of donations he made.

But Mr Stevens said: “He was the one that found the donors so it’s possible that he didn’t tell his wife and she believed the donations were coming from a lot of different men.”

Current guidelines dictate sperm from British donors can be used for a maximum of 10 families, with no limit on the number of babies within those families.

A commission in 1948 said artificial insemination should be banned.