The Greenwich Time Signal or BBC pips
BBC pips are six short pips, starting at five seconds to the hour and ending on the hour. They were first transmitted at 9.30 PM on February 5th, 1924.
First pips were synchronised with Greenwich Mean Time. From 1971 the pips are synchronised with International Atomic Time.
You can read the full story of BBC pips on Michael Todd website.
Listen to 1995 record of BBC World Service Lillibullero with BBC pips on YouTube: