It was Christmas 1906 and the Reverend Percy Dearmer was making preparations for services at his Primrose Hill church.
The Kilburn-born clergyman was selecting carols for his congregation to sing at St Mary The Virgin and its likely that he chose brand new tunes along with old favourites.
That May, along with Martin Shaw and celebrated composer Ralph Vaughan Williams, he had published The English Hymnal, a new tome that used traditional English folk tunes to modernise what they thought of as dour Victorian hymns.
The introduction to the green-backed book proclaimed it as "a collection of the best hymns in the English language". O Come All Ye Faithful, Hark! The Herald Angels Sing, Away in a Manger, Silent Night, Once in Royal David's City and While Shepherd's Watched were among the existing carols they selected.
But there were new settings and tunes - and brand new carols - including Christina Rosetti's 1872 poem A Christmas Carol set to a tune by celebrated composer Gustav Holst.
Vaughan Williams had asked Holst to pen a tune as part of the two-year project to produce the hymnal and he named it Cranham after the Gloucestershire town where he lived.
The beautiful music and words came together in In The Bleak Midwinter which, with the release of sheet music to accompany the book, swiftly took off to became one of our best loved carols.
Vaughan Williams had also taken a folk song The Ploughboy's Dream and turned it into Forest Green, a new tune for the existing carol O Little Town of Bethlehem - first published in The English Hymnal and now so familiar today.
Both were first heard at St Mary's in the early years of the 20th Century.
Martin Shaw became the organist at St Mary's and together with Rev Dearmer and Vaughan Williams they published The Oxford Book of Carols in 1926, which became so widely used by congregations that it is now the playlist for Christmas services and carol concerts.
They also published Songs of Praise in 1925, which included the new hymn Morning Has Broken - with words by Hampstead children's author Eleanor Farjeon, who was commissioned by Dearmer.
An avowed socialist who would welcome the homeless into his vicarage, Rev Dearmer left Primrose Hill in 1915 and set off with wife Mabel to become Chaplain to a Red Cross ambulance unit in Serbia.
Sadly Mabel died of typhus that year - as did their son Christopher, who was serving at Gallipoli.
Rev Dearmer was later appointed Canon of Westminster Abbey where he ran a soup kitchen for the unemployed. He died in 1936 and is buried in Westminster Abbey.
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