I would hestitate to speak for all Britons, but those I know are all just fine with NATO being involved in Afghanistan. It's certainly preferable to ad-hoc coalitions of the cajolled with no real standing as internationally approved organisations. Indeed, there's probably a case to be made for dropping the "North Atlantic" part of the formula and broadening NATO into a Global Treaty Organisation as the de facto arm of the UN for peacekeeping purposes, one any member could call upon for assistance against an attack.

Of course, there's no way Article Five could have been invoked by NATO in respect of Iraq. There was no Iraqi attack to respond to. That and a lack of UNSC authority help show that the Iraqi invasion itself was an illegal war of belligerence, even if the occupation which followed it has been made legal in international law by a UN mandate. It isn't impossible that war crimes charges at some future date could note that distinction.

Regards, C