It is based on a railway journey Thomas took on 24 June 1914, during which his train briefly stopped at the now-closed station in the Gloucestershire village of Adlestrop.
He noted down the grass, the willows, the willowherb and meadowsweet, the blackbirds and silence interrupted by the hiss of steam at these two stops.
[2][3] Since then, the poem has become a symbolic turning point in Thomas's literary career, and is used as such in the title of Jean Moorcroft Wilson's 2015 biography of the poet.
Adlestrop village also held a celebration to mark the centenary, with a public reading of the poem by Robert Hardy.
And willows, willow-herb, and grass, And meadowsweet, and haycocks dry, No whit less still and lonely fair Than the high cloudlets in the sky.