It was he who first applied to the Performing Rights Society for the right to claim authorship over his compositions and when he was successful so did Delia. It is thanks to him that she retained any of the rights to her BBC works.
His brother writes:
He reached an accommodation with the ethereal Delia Derbyshire, although he privately criticised her academic background, believing she was more a mathematician than a musician.
After John died in 1997, Delia visited Daphne, the companion of his final years, at their home on the Isle of Wight.