Harry Potter star Sir Michael Gambon who plays Hogwarts headmaster Albus Dumbledore in the Harry Potter franchise had the child with his mistress Philippa Hart.
A family friend said: "Philippa gave birth at a London hospital without complications and little William is a beautiful bouncing baby. It is a very strange set of circumstances worthy of a film script in itself. "
Michael Gambon joined the Harry Potter films in the third instalment, The Prisoner of Azkaban, after the original Dumbledore Richard Harris died.
A family friend said: "Philippa gave birth at a London hospital without complications and little William is a beautiful bouncing baby. It is a very strange set of circumstances worthy of a film script in itself. "
Michael Gambon joined the Harry Potter films in the third instalment, The Prisoner of Azkaban, after the original Dumbledore Richard Harris died.
The next film, Harry Potter and the Half Blood Prince is out at cinemas in July
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