No buskers around and it was way too good to be a busker anyway. Me and another guy were looking round and staring at the ceiling to see where the sound was coming from. Hardly anyone else looked remotely concerned, particularly a couple of station assistants chatting in the corner.
It was about 11.30, and not many people about, but I certainly didn't notice it when I went steaming through the station and a few hours before. So I asked the station assistant who it was. He didn't know and said "It's just a compilation one of the guys has done from his computer - there's no label on it"
So yet another mystery. It was definitely a piano concerto, something like Satie but definitely not as contemporary. But whatever it was quite soothing, perhaps it will catch on at other stations.