Johnny Mercer served in the British army for twelve years. A captain in 29 Commando, he was deployed on three tours of Afghanistan, and weathered some of the heaviest fighting of the campaign.

He left the army in December 2013 with the aim of becoming an MP, in the hope he could improve care for armed forces veterans. He was elected MP for Plymouth Moor View in May 2015 and has since led an inquiry into the treatment of troops by the Iraq Historical Allegations Team.

Tim Hopgood was six years old when he first heard Louis Armstrong's recording of "What a Wonderful World." Years later his daughter found a recording of the song in a flea market and gave it to him as a present.

As soon as he heard Louis Armstrong's gravelly voice sing the first few lines, he knew he wanted to capture the joy of the song in a picture book.