David Bowie was a regular customer there in the late 1960s and early 1970s.
Comment from a thread on the Beckenham History Forum website, 2011:
Name: Brian Vickers
Comment: I played in a band called The Burnettes during the early sixties with all sorts of people who were around Beckenham at the time. Met David Jones (now Bowie) when he played sax for the Konrads at Justin Hall, and Peter Frampton when he played in The Trubeats and then The Herd. We cut a demo disc in Robertson's music shop, which was on the bend of Beckenham High Street, on the day of Winston Churchill's funeral in 1965. They had a record section upstairs and a small recording studio too, which was being manned that day by Peter Frampton behind the desk!