Mar 30, 2017, 1:29
The singer had fans in a frenzy when he sat at one of the pianos provided at the station for travelers to play while waiting to catch a train.
The three pianos in St Pancras station are hugely popular, with hundreds of visitors sharing their performances on social media over the years.
Legend teased fans ahead of his arrival in the capital and asked his Twitter followers if the piano was still at the station.
John, 38, sang his hits Ordinary People, All of Me and Surefire for ecstatic onlookers, who pulled out recording devices to capture the moment.
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Legend hinted that he was planning to perform in a tweet, sent just as he was arriving from Paris. "Do they still have that piano there?"
There's a public piano there and Legend, who just arrived in London, chose to give all the fans a special treat on their way to work.
The singer is promoting his forthcoming world tour, which is due to reach the United Kingdom in September. Watch back a live stream of the performance below.
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