Inside the multi-million dollar scramble for a top hit on the festive music charts. How can new artists take on the likes of Mariah Carey and Slade? Katya gets answers and music – lots of it – from the BBC’s music correspondent Mark Savage, and writer and musician Chris Lochery.

Warning: this episode may leave you humming.

The Global Story brings you trusted insights from BBC experts around the world, with Katya Adler. We want your ideas, stories and experiences to help us understand and tell The Global Story. Email us at theglobalstory@bbc.com You can also message us or leave a voice note on WhatsApp on +44 330 123 9480. #TheGlobalStory

Today’s episode was made by Neal Razzell, Farhana Haider and Emilia Jansson. The technical producers were Matt Hewitt and Ben Andrews. The assistant editor is Sergi Forcada Freixas and the senior news editor is Jonathan Aspinwall.

The Christmas number one formula (and why old songs do best)