Sorry, Bookworm
Correct ref: MATS Part 1, Sect 1, Ch 2, FLIGHT RULES, Para 4, Note 3.
It's the rule, the law, if you like, that flight vis in the zone is determined by ATC using A/D Met report AT THE AIRPORT. Applies to all the zone irrespective. So even if you claim to be VMC you can't have VFR if MET is against you.
Check the UK Air PIlot also. Same rules. All Zones. All ATCOs.
Pa!