White Cliffs of Dover song
The song is no longer copyrighted in most countries because it was written over 70 years ago. However, if you do use the song, please honor its lyricist and composer (as I have done) by crediting them.
Interesting tidbits on the song
Bluebird issue
Nat Burner was an American who had never come even remotely close to England. That explains why he mistakenly incorporated the bluebird in his song. The bluebird is an American, not a English bird, so you're not going to see "blue birds over the white cliffs of Dover".
Impact
We can forgive his bluebird slip-up because his war-time verse stirred the hearts of the English when it was needed. It reflected and reinforced the faith that the future would once again be pleasant and peaceful for them and their children when the dreadful war ended.
Vera Lynn
Many singers recorded the song in Britain and America. The most associated with it is England's Vera Lynn. Her other famous morale-raising song was "We'll Meet Again". It was even more popular in England than her "White Cliffs of Dover" recording. For those and other efforts, she was later knighted by Queen Elizabeth, becoming Dame Vera Lynn.