I was in Swansea again over the weekend. I believe there are at least 14 blue plaques in the city. I saw these two. The first is at the station and the second is near by on Ebenezer Baptist Church.
Pete Ham was a member of Badfinger, the first act apart from the Beatles to appear on the Apple label. Sadly, he became a member of the 27 Club when he committed suicide in 1975. A posthumous album of his home recordings is called Golders Green, noting his residence when the recordings were made (the other was called 7 Park Avenue for the same reason - there is no blue plaque there; it's round the corner from me).
As for Griffith John, he was by contrast a pioneer missionary to China, who translated the Bible into Chinese languages. A new bitesize biography of him by John Aaron has recently appeared.