This is not a carol, but a 19th-century American hymn. But the tune associated with it in Britain, Forest Green, was collected by Vaughan Williams in the Surrey village of that name in 1903.

My mother never cared for O LIttle Town, but "The hopes and fears of all the years" is one of the lines that did it for me as a child, along with "And dark is his path on the wings of the storm" and "The purple-headed mountains".