I know you will all laugh at me for being like the accountant and splitting hairs but the 1.6m Muslims doesn't count all the people who might hold British passports but who were not in England and Wales on census day in 2001, but instead were elsewhere (maybe even in AQ camps?!) This can lead to significant deviation in the true numbers of all those who might be considered "British-based". This is especially the case for countries in the Commonwealth where migration and dual nationality are common.

Viz the dreaded KiltGuy: technically a Canadian citizen, has a passport and ID card etc, would be the first to wave his Canadian nationality around if ever drafted into anything unpleasant in the UK, but has visited The Big Maple only three times in the last ten years.