The "Piano Man" was found by Kent police walking around the town of Sheerness. He was dressed in an expensive suit and tie, but was soaking wet.
He has not spoken since being picked up by the police, but when given a pad and pen, he drew a detailed image of a grand piano, complete with the instrument's inner workings.
Michael Camp, his social worker, brought him to a piano in the hospital chapel, and the unidentified man sat down and gave a two-hour performance of classical music. He continues to play, and has written some music.
An unconfirmed report has it that he played a "beautiful" performance of Tchaikovsky's Swan Lake.
A spokeswoman for the West Kent NHS Trust said, "There was nobody he was with skilled enough to recognize the music, they just knew it was classical music and he played very well."
His playing, according to Camp, "amazed everyone who has heard him. It is difficult to stop him and he sounds concert standard. When he plays all his anxiety disappears. Away from the piano, he starts to breathe very quickly and shies away from people."
The man's picture has been published in the national press, and a telephone number has been set up to collect information. Someone has called with a possible lead, the name and address of someone in Sussex who may or may not be the "Piano Man."
Camp hasn't yet followed the lead, and hasn't been able to contact the person who called it in. "We had one of these before," he said, "from the local area, and it sounded promising, but. . . people start to think 'It might be this person that we know' and it doesn't quite materialize. We'll just have to wait and see."
The U.K. National Missing Persons Helpline is at +44 (0) 20 8392 4509.