From Youtube description:
Sailing By by Ronald Binge in 1963, theme tune to the BBC Shipping Forecast
Sailing By is played every night on BBC Radio 4 at around 00.45hrs before the late Shipping Forecast. Its tune is repetitive, assisting in its role of serving as a signal for sailors tuning in to be able to easily identify the radio station. It also functions as a buffer — depending on when the final programme before closedown finishes, Sailing By (or part of it) is played as a 'filler' as the shipping forecast starts at 00.48hrs precisely. The initial reason for its introduction was because of the indeterminate finish time for the preceding Midnight News, leading to filling music being played until the Shipping Forecast was due to start. Sailing By was added to allow for a clear break between the end of the music and the start of the forecast.
In the 1990s the tune was also adopted for the weekly maritime programme Seascapes on Ireland's RTE Radio 1.
Besides its intended function, Sailing By is thought of affectionately by many British radio listeners as it is considered a soothing accompaniment to bedtime. The lead singer of the Britpop band Pulp, Jarvis Cocker chose Sailing By as one of his Desert Island Discs, saying for many years he had used it "as an aid to restful sleep".
The piece featured as the second track on a single recorded by the Royal Ballet Sinfonia in a quest to save the Radio 4 UK Theme. In 1993 there was a similar reaction by BBC listeners when Sailing By was temporarily taken off the air on weekday schedules, leading to it being re-instated in 1995.
The recording used by the BBC (performed by the Alan Perry/William Gardner Orchestra) was originally only available as library music, but has since 1997 been available commercially as track 11 on the second CD of the EMI CD set titled The Great British Experience (EMI Classics CDGB50). The BBC broadcast the original stereo version for a few weeks in the late 1980s, but soon reverted to a mono version.