Thanks - the database integrity check passed, shut down strawberry, and recreated songs_fts but on restarting I see the same problem. Full collection rescan?
Maybe related after the restart I was trying various strings in the search bar and SMP crashed on me. Last line on .xsession-errors (maybe from SMP) was kf.i18n: "1 instead of 2 arguments to message {by %1 (%2)} supplied before conversion."