I applied through college or university. The process took 2 days. I interviewed at Barclays in Oct 2011
Interview
It started off with a application and a test to be taken. The application had a few essays to be written which I guess anyone who has interest in the field can manage. After the application procedure is complete you will have to take a test immediately. The test has two parts - one is a data interpretation and other is analytical and logical reasoning. You'll have a set of practice questions before the test. Analytical and logical reasoning is pretty easy in terms of time management but with DI you have to be fast in number crunching.
Once you clear these tests, they'll shortlist you based on your application and performance in the test.
The interview process had 3 stages. A group Discussion, a case Study, Group/panel interviews.
GD and Case study are very random topics which keep changing every year so it was much of your spontaneity and decision making skills. I had cleared the GD and Case study. So, I had the PI. In the PI they asked only what you portray in your CV. So, the questions are person specific.