What happened to Clifton Jones?

There's a thread about this on his IMDB entry (and an old post on this message board). Somebody recently came forward and said that he was last known to be sleeping rough in London. I know that the organisers of a recent convention tried to trace him, but this sadly came to nothing. Also heard a rumour he has failed to claim some money which is owed to him in royalties. A tragic story which we'll probably never know the answer to.