If you've heard Sam Smith's swoonsome 'Lay Me Down', you'll be aware that it's proven one of the more popular cuts from his million-selling debut album 'In the Lonely Hour'.

Well, how do you make a popular song even more popular? By adding John Legend to the mix.

Smith has re-recorded the track with added vocals by Legend, all in aid of Comic Relief. The song is available to buy online from iTunes from today.

They'll also perform it live from London on Friday (Red Nose Day).

Watch the video below: