I've been reading through their 2013 Statistical Yearbook report - as its a cool 252 pages long, the following are just a few of the many points you can pick up from a skim or a more leisurely read yourself.
2013 BFI Yearbook - Selected Points
Note: Definition of ‘UK film’Only the US and Japan have a larger 'filmed entertainment' market than the UK (valued at £4bn).
For the purposes of this chapter, a UK film is one which is certified as such by the UK Secretary of
State for Culture, Media and Sport under Schedule 1 of the Films Act 1985, via the Cultural Test, under one of the UK’s bilateral co-production agreements or the European Convention on Cinematographic Co-production, or a film which has not applied for certification but which is obviously British on the basis of its content, producers, finance and talent. Most UK films in the analysis (including the major studio-backed films) fall into the first group – films officially certified as British. [p.76; see longer quote at the end]