OutsideCAS - "I", not "i" - ah c'mom, you asked for that.... ;-)
My take is that a UK-registered aircraft operating public transport are workplaces and thus are subject to DoH legislation on smoking in workplaces, I.e. No smoking.
I would guess at a foreign registered (M for instance) aircraft operated by a UK company with UK contracted crew having the same problem.
VP-B etc with non-EU contracted crew would probably not be subject to it.
Personally, it stinks, I defend your right and all that, but it stinks. If I were paying £3500 an hour for a jet I would not want it to smell of Ambi-Pur, just normal air...