The first Festival of Nine Lessons and Carols in King's College, Cambridge was held on Christmas Eve in 1918. The format did not differ substantially from the one known today. The service was first broadcast on the British Broadcasting Corporation in 1928, and since the early 1930s has been broadcast live to many parts of the world on the BBC Overseas Service. It is estimated that each year there are millions of listeners worldwide. There is also a television broadcast in the UK, although that is pre-recorded in mid-December.
The service traditionally begins with the hymn 'Once in Royal David's City', with the first verse sung unaccompanied by a solo boy chorister, and ends with the hymn 'Hark! the Herald Angels Sing'. The lessons are read by representitives of the college and the City of Cambridge. The singing is divided into 'carols', which are sung by the choir, and 'hymns', sung by choir and congregation. A new carol or a new arrangement is frequently premiered at the service.
The format was based on an Order drawn up by E.W. Benson, later Archbishop of Canterbury, for Christmas Eve 1880. It has since been adapted and used by other churches all over the world.