David Bowie was 22 years old and still living with his parents in southeast London when, quite by chance, he met Mary Finnigan while visiting her upstairs neighbours in nearby Beckenham. Still an unrecognised talent haunting the London folk clubs, desperately seeking paid gigs, he couldn't even dream of a future as a global rock phenomenon.

Life started to take interesting turns after he moved in with Mary and her two children in the spring of 1969. With a small group of psychedelic pioneers, they launched the Beckenham Arts Lab in a local pub and organized a free music festival in...