Comment 41 by Simon Templar :

From your (and indeed my) POV it is conjecture but I'm merely suggesting that being a bishop he would have access to the population figures for the C of E based on Church records which possibly or even may I dare say probably shows around 71% of the current British population are shown to be baptised into the C of E.

FFS, does nobody read my posts.

From this page

'What is your religion?', the question in the 2001 census used in England and Wales gave a far higher figure for ‘Christian’ than all other surveys. The 'Christian' box was selected by 71.74% of respondents in England and 71.90% in Wales. The Scottish figure, where respondents were asked about the religion they were brought up in, as well as their current religion, showed significantly fewer respondents ticking 'Christian': 65.08%