New singles which were received by the pirate station Radio London and approved of by the station's programme director were featured in the station's playlist for at least one week, and referred to by the DJs as "Radio London Climbers". The station prided itself on being several weeks ahead of the national charts, so some "climbers" appeared on the playlist before their official release. Many of them made the Radio London Fab Forty, some of these later appeared in the official pop charts, while others failed to make any impression.