Dame Vera Lynn's classic wartime song is British, original and entirely without controversy, or not. Ian Hislop discovers the chequered history of this musical mainstay of the British nation in its finest hour. Could it really be a song weighed down by politics, propaganda and even a touch of plagiarism? And what about those bluebirds - have you ever seen any in the Dover area? Hislop meets Dame Vera, veterans, musicologists and, yes, an ornithologist, in his quest to find the hidden meaning of this enduring wartime song.

Ian Hislop looks for bluebirds: page 123