1-3 days really quick. But then again, I live in London, away from my University and the most annoying and time-consuming part of inter-library loans is sending the copyright deceleration to my University's library. They can't start the application without this hard-copy deceleration. On a few occasions, I had to wait around 3 weeks because it took ages for British Library to respond to my University. So in some cases, going to the British Library works out easier.