Steve Mac and Ed Sheeran "wrote 20 songs in five days" during an intense studio session.
The 46-year-old songwriter - who co-wrote Ed's Grammy award-winning 'Shape of You' track - has revealed that he and the ''Castle on the Hill' hitmaker "write songs all the time" because once they start the creative process, it becomes hard to stop.
Speaking exclusively to BANG Showbiz, Steve said: "We write all the time, about two months ago we were in the studio for five days and we wrote 20 songs and it was an incredible thing, you know the man is just a machine when it comes to songwriting."
The British musician has worked with the biggest names in the industry including Westlife, Liam Payne, Rita Ora and Pink on her 'What About Us' track.
The 'Flying Without Wings' co-writer confessed that he believes all 20 tracks "will get cut" and could be kept aside for Ed's fourth album or be given to different artists "looking for a new single".
Steve added: "So we've got 20 songs, some of them maybe for him for the future, some of them maybe for other artists, I think they are all going to get cut. Towards the end of the process you can pick artists out in your head.
"My relationship is normally with the labels and you play the songs to them and then they let you know who they have got and whose looking and whether there's a single available."