This has to be the barmiest idea yet — in thrall to the Ecofascists' Boiling Frog fantasies, but frightened that 'economic growth' will falter (along with campaign contributions if they take on the airline lobby) should they actually hike travel taxes again, Britain's Jacobins now want the nation's Great Unwashed to fork over the cost of an onboard lager voluntarily in order to 'save the planet' from the effects of their unthinking hedonism!
What's next — a couple of quid to Leviathan to salve your conscience everytime you eat a Big Mac (a lipid-'obesity' offset), or a tenner to the bureacrats whenever you visit an art gallery (a 'social exclusion' offset)?
