In England and Wales, there were 37.3 million Christians in 2001, representing 72 percent of the population. In the most recent census (2011), that had dropped to 33.2 million or 59 percent of the population.
Religion News Service had a brief story about this that included these graphs:
Figures from the 2011 Census show the number of people declaring themselves to be atheists rose by more than 6 million, to 14.1 million.
"It should serve as a warning to the churches that their increasingly conservative attitudes are not playing well with the public at large," said Terry Sanderson, president of the National Secular Society. "It also calls into question the continued establishment of the Church of England, whose claims to speak for the whole nation are now very hard to take seriously.”
However, those statistics are not right.
As reported in The Telegraph:
The number of people specifically identifying as Atheists was 29,267, while over 13.8 million refused to identify with a faith at all, ticking the "No religion" box on the census form.
While reporting no religion might sound similar to atheism, there is no way for journalists to know if respondents are atheists, agnostics, unaffiliated or otherwise.