Cash was born in Bushey, Hertfordshire, in 1942, and grew up in London. He began his career in broadcasting in Canada; he visited the country while in the British Merchant Navy, and acquired a North American-sounding accent. He returned to the UK in the 1964 and joined pirate station Radio London at the age of 21 after meeting up with the programme director, Ben Toney. Toney persuaded him to join the station as the afternoon DJ and writer for commercials. Once on board with Radio London, Cash teamed up with Kenny Everett for the "Kenny & Cash Show", amongst the most successful of all pirate radio programmes.