Alongside the picture, which showed him surrounded by onlookers as he played, he wrote: "Surprise!! I popped into St Pancras International to christen the Yamaha piano which I donated to the station. Now everyone can have a play."
He then shared a close-up picture of his note on the instrument, alongside a quote referencing the lyrics to his track 'Your Song'. WATCH: Elton John performs at St Pancras London!!