"Yesterday" is often interpreted as a melancholic ballad about lost love. Paul McCartney later suggested that the lyric 'I said something wrong' may have been inspired not by romance but by a childhood memory of mocking his mother for sounding 'posh'. McCartney's vocal and acoustic guitar, together with a string quartet, was essentially the band's first solo performance. It remains popular today and is one of the most covered songs in history of recorded music. The final recording was so different from other works by the Beatles that the band members vetoed the song's release as a single in United Kingdom. But in the rest of the world is was a big smash, published on September 13, 1965, it reached no.1 in the United States, the Netherlands, Belgium, Sweden, Norway, and Finland, furthermore no.2 in Australia and New Zealand.