Birkin is the only son of Lieutenant-Commander David Leslie Birkin (grandson of the lace manufacturer and railway director Sir Thomas Birkin, 1st Baronet) and his wife, actress Judy Campbell. One of his sisters was actress and singer Jane Birkin.
Birkin is the sole offspring of Lieutenant-Commander David Leslie Birkin (grandson of the textile manufacturer and railway administrator Sir Thomas Birkin, 1st Baronet) and his spouse, actress Judy Campbell. One of his sisters was actress and singer Jane Birkin.