Actually - the 'dominant faith' issue is now skewed because of the large number of East Europeans working temporarily in the UK. They are largely Catholic, which has resulted in a 'bump' in Catholic church attendances!
I think the major difference between those who follow the Christian, Hindu, Muslim and Jewish faiths in this country, is that non-Christians really identify themselves with their faith. It's very central to their self-image.
However, 'Christians' fall into two distinct groups - those that read Bible passages to their kids, regularly go to church, activitely support church activities in the community, know the scriptures, pray etc...
And then there are people who will fill in 'Church of England' on forms - because they know they are not Catholic (or Jewish, Hindu etc). I don't think they are saying that they are Christian in a proper 'Cliff Richard kind of way'