In the end I looked on 50.230MHz last night, but only copied G4BAO who was working an OZ. I suspect I was copying John directly and not off MS pings. Tonight I'll try the newer JT6M frequency further up the band. Now back on 6m WSPR during the day and early evening.
UPDATE 0915z: Plenty of 6m WSPR spots of G0OQK (98km) by tropo and aircraft reflection. He has also spotted me lots of times again.
UPDATE 0938z: There were no overnight 10m WSPR spots. I thought I might have been spotted in Europe via the Perseids by MS but guess the 2 minute TX period, low power and Doppler were all against me. MS pings are much longer on 10m. In the past I have worked QRP SSB DX by 10m aurora but never tried 10m MS. Maybe I should. It is a pity there is not a 30sec WSPR mode!