"Who'd Have Known" is the fifth and final international single (fourth and final in the United Kingdom) by British recording artist Lily Allen from her second studio album, It's Not Me, It's You. Written by Allen and Greg Kurstin, while interpolatingTake That's single "Shine", the song was released as the fifth and final single from the album on 30 November 2009 by Regal Recordings. Contemporary critics complimented the song and Allen's warm vocals, while the music video portrays her as a groupie of Elton John.
The song is prominently sampled in American rapper T-Pain's 2011 song "5 O'Clock", on which Allen is credited as a featured artist.
Before the release of the album, Allen posted the song, then titled "Who'd of Known", on her MySpace account, revealing that she sampled Take That's single "Shine" and wrote: "I ripped off the chorus from Take That and can't be bothered with the paperwork.", for which the single was almost not included on It's Not Me, It's You. The singer pointed out in an interview that "Greg [Kurstin] just played the chords and I sang and we were like, 'That's great, really hooky.' Then when we played it back to someone, they pointed it out that it was, essentially, 'Shine'", and, while the band did not agree to sing on it, they gave her permission to record it, as they liked the song. The group was also credited as co-writer.
When reviewing the album, Jody Rosen from Rolling Stone magazine called the song a potential single, being "the ballad with the album's most surefire hook". Neil McCormick from The Daily Telegraph noticed the song in particular, claiming it to be a "tender evocation of friendship turning to love", while Allen's vocals highlight affection. He also added that, on tracks such as this, "Allen still sounds like a real person telling us the most intimate details of her real life, only with better hooks".Drowned in Sound reporter James Skinner suggested that the song "lucidly details the furtive thrills and giddy excitement that lie at the outset of a romantic endeavour" and, in comparison with "Shine", "in slowing the tempo some though, substituting its vapid generalities and platitudes with a warmth both insightful and agreeable, she bests the original considerably". Ryan Dombal from Pitchfork Media concluded that the song "is prime Lily 2.0, growing up without the heavy-handed, 2D 'maturity'; it's a knowing ode to early love and all the uncertainty, excitement and irrationality that goes along with it".
Allen and the Elton John lookalike in the music video for "Who'd Have Known".
The music video for "Who'd Have Known" captures Allen as an obsessed fan of Elton John. It starts off with her character lying in bed, watching Elton John's concert on television, while DVDs and magazines portraying him are scattered throughout her room, with a big poster of him on her wall. John, portrayed by an actor, receives a letter from the singer declaring her love, accompanied by a badly photoshopped picture of the two of them, but ignores it. Upon exiting his home, he gets in a car to discover that Allen is in fact the driver. She locks the car doors, kidnaps him, and takes him to her home, where she ties him to a chair. There, she plays the piano, drinks wine, skims magazines, hugs him, makes him eat and draws a portrait of him. Afterwards, she puts a telephone to his ear and makes him say "I want you to know that I have fallen deeply in love with Lily" to an unknown receiver. Afterwards, they both sit on the sofa, watching John perform at the piano on TV. As Allen falls asleep, he manages to wriggle free from the tied ropes on his feet. The video ends with John taking a final glance at Allen asleep before escaping from the building and running off.