As I was getting no results (apart from G6AVK earlier) on 6m, I have decided to QSY down to MF for the rest of the evening and overnight. I am still using 5mW ERP from the earth-electrode "antenna".
Already, I have been spotted by G7NKS (46km), M1GEO (79km) and G8LCO (58km).
So far I have copied G3ZJO (79km), G7NKS (46km), G0LRD (25km), G4KPX (14km) and G8VDQ (93km).
I've only been on the band for about 15 minutes. It is currently 2211z. There are currently 61 active stations on 472kHz WSPR.
UPDATE 2300z: Also now copied DK7FC (669km), G8HUH (250km), M0PPP (182km) and PA0A (417km) on 472kHz WSPR. All stations that I have copied before.
An observation on 472kHz operating: there are those who take 472kHz (and 137kHz) very seriously and who invest serious effort on rigs, antennas and ground systems and those, like me, who take MF and LF altogether less seriously and attempt to get results with the simplest systems. DK7FC is certainly one of the first type: he puts out excellent signals on MF and LF and is widely copied in the USA, something I could only dream about.