To pick up on one of your earlier points, all landings below Cat 1 minima are reported to the CAA
Not strictly true as I recall. It was all landings carried out whilst RVRs were reported (commonly in vis conditions <1500m). It was something that the airport authority had to do so at a big airport like LHR ATC may not have had any active involvement beyond recording the RVR (which they would probably do anyway).
But it hasn't been done for several years to my knowledge.
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And another thing, MANTHRUST, the reason that the rigid rules are in place in some parts of the world today is because when pilots were allowed to make the judgement they go it wrong more often than the authorities - and the passengers - could tolerate.