Ed Sheeran has marked his 26th birthday by releasing a song that he completely forgot he had written.

Describing the track - How Would You Feel (Paean) - as one of his favourites, he admitted he had to work fast to fit it into his upcoming album after discovering it hidden in his girlfriend's email inbox.

Speaking to Zane Lowe on Beats 1, he said: "My partner came back to Suffolk and on her way to the airport I wrote that song, recorded it on an iPhone, sent it to her and forgot about it."

When his Divide album was completed, he explained how he asked girlfriend Cherry Seaborn what her favourite track was and she said: "My favourite song you don't actually know exists."

I went in and recorded it very quickly and produced it all up and it's one of my favourite songs on the record

After she played him the forgotten tune, he said: "I went in and recorded it very quickly and produced it all up and it's one of my favourite songs on the record."

Sheeran fans have described the song, which starts with the lyrics "You are the one, girl," as his best love song so far.

@Mariana_m01 Tweeted: "The very best birthday to the love of my life...Paean is the most romantic song ever."

@casingalmicah added: "How Would You Feel (Paean)'s lyrics was so perf! I think I just fell deeper in love with you."

@MeyLovesCupcake posted: "As if you are singing to me. Love you much!"

Meanwhile, others have been just as keen to congratulate the singer on his own special day.

After he posted the simple message "26" on his Twitter account, @AidanJames replied: "Happy birthday, thanks for being one of my biggest inspirations!"

Others jokingly responded "27", "28", "29" and so on - up to five-figure numbers.

Divide is due to be released in March.