You make an interesting point too...
- I recall MK say 19.5A total continuous rating.
- So MK will probably argue "20A DP switch to 2G socket is fine".
Diversity applies: few people have 2 tumble dryers on a 2G socket.
If you go further I suspect at least 5% of all UK rings are broken on L or N and so are effectively a 32A radial on 2.5mm cable - that results in "brittle sheath or impossible to strip insulation" eventually :-)