All opinions uttered here are strictly my own, though if you disagree with them you are objectively wrong!
England has given us only two truly great composers. Other English composers have given us great music to be sure (Blake/Perry's "Jerusalem", Elgar's Cello Concerto, etc) but only Tallis and Vaughn Williams stand out as giants in my mind, having written multiple works that had they been written by anyone else, would be considered that composer's greatest contribution to humanity.
Thomas Tallis is most well known as being the court composer for Henry VIII, Edward VI, "Bloody Mary", and Elizabeth I. It was during the reign of that first Queen Elizabeth that he wrote what is probably the first truly great piece of English music.
It's a motet in 40(!!) voices called "Spem In Alium" ("No hope in any other").
If all of the stars shining above on a cold clear night could sing, it would sound like this.
"a queer, mad work by an odd fellow from Chelsea"
Thomas Tallis was the greatest of the English composers.... until Ralph Vaughn Williams early in the 20th century. (Trivia: his first name is pronounced "Rafe")
Among Vaughn Williams momentous achievements was adapting a few short themes from a little known and seldom performed motet by Tallis and weaving them into a sweeping orchestral work. This work, "Fantasia on a Theme by Thomas Tallis" is part folk-song, part hymn, speaking suffering and triumph, desolation and beauty.
When it was premiered at Gloucester Cathedral in 1910, reviewers (and the audience) didn't quite know what to make of it. One reviewer summed up his impression in the quote above: "a queer, mad work by an odd fellow from Chelsea"
While having initially caught audiences off guard, it grew quickly in acceptance and recognition. The "Fantasia" was a popular and oft performed work during WWII, so much so that it was occasionally referred to as England's wartime anthem. When this current war against a virus is over and the dead mourned, if a local symphony orchestra should include RVW's "Fantasia" in an evening's program, I hope you'll go and hear it.
Not all listeners were as caught off guard as the reviewer above. Another reviewer, speaking of that same premiere wrote:
"Throughout its course, one is never quite sure whether one is listening to something very old or very new."
The version I've selected to share is a stunning new rendering by the London Philharmonia, recorded in 2020.
Ralph Vaugh Williams, "Fantasia on a Theme by Thomas Tallis"