I've just got a temp controlled fridge so about to do my first cold conditioning of a British ale. From what I've read in the forums, it seems that most people crash the temp down as quickly as possible after the end of the diacetyl rest. However, I've read in White and Zainasheff's Yeast book that "very rapid reduction in temperature (less than 6 hours) can cause the yeast to excrete more ester compounds instead of retaining them". I'm not sure if this is really a problem in an English ale, but was curious to know what peoples thoughts were on lowering the temp fast or slow. If slow, how slow? I started at 20 degrees C for a week, then went to 23 degrees for 4 days to finish off ferment and do diacetyl rest. I was then going to reduce it from 23 to 2 degrees C.