The BBC reports on the proportion of potential new citizens to pass the citizenship test. The overall pass rate was 70.9%, and to pass requires answering at least 18 questions out of a 24 question test correctly.
When the test was first announced, this sample test (flash-based, might not be very accessible, at least two of the questions on the sample test have answers that are not strictly true) got passed around various forums. Numerous UK citizens had a go at it.
The pass rate for UK citizens, I think, was between 10% and 20%. Without cheating and looking things up on the internet, I got 13 out of 24, which is nowhere near enough, but was a fairly typical score. It should tell you how useful some of the knowledge tested is to being a UK citizen, anyway.
There's a booklet that one can get before taking the test, that goes through the facts that might be tested. What the test is actually testing is that:
- You can read English well enough to read the book and then interpret the questions.
- You have a good medium-term memory for apparently pointless facts.
Unsurprisingly, the pass-rates for migrants from countries where English is an official language are really high (presumably the people who failed were those who were never any good at exams, and/or had disabilities that made the test environment inherently unfair), and the pass rates for migrants from other countries were much lower.
It's in keeping, of course, with the country's apparent need to be unfriendly to immigrants (while remaining reasonably friendly to ex-pats) that it sets a test for citizenship that the majority of the existing citizens would never pass without practice.