Promos are often distributed in plain packaging, without the text or artwork that appears on the commercial version.
Typically a promo is marked with some variation of the following text: "Licensed for promotional use only.
Quite often, vinyl records will be issued in a generic cardboard jacket or white paper sleeve while CDs will be issued in a slimline jewel case or cardboard sleeve.
More than 10,000 CD singles from the 1980s to present day also filled up a spare bedroom of his modest home in Twickenham, south west London.
There were dozens if not hundreds of CDs still in their cellophane wrappers from where he hadn't had the time to open and listen to them.
The archive contains the good, the bad and the downright ugly that graced the shelves of record shops across Britain for over six decades.
There is everything from Abba to ZZ Top, including all 39 Beatles singles and re-released singles, the 52 Rolling Stones' chart hits and the 72 songs released in the UK by Elvis.