As the storm risk seems to have passed, I have resumed 472kHz WSPR (5mW ERP 20% TX, 80% RX, earth-electrode "antenna") using the FT817 and homebrew transverter.
UPDATE 1922z: So far only M0LMH (223km) has spotted me twice. He regularly spots me.
UPDATE 2000z: Not for the first time, I find myself, yet again, the only UK station transmitting 472kHz WSPR. I just don't understand why this is when transverters are easy and big antennas are not needed for WSPR.
UPDATE 2220z: Now WSPRnet is playing up and won't load the database with me! "Problem loading page". Wonderful. I'll stay on 472kHz overnight but without WSPRnet WSPR is not good. WSPR benefits from the internet feedback/reports that WSPRnet provides. One cannot be sure if reports up to WSPRnet are getting through. As many users have said, we'd be happy to pay towards a reliable service. Clearly the database and its maintainers are struggling currently