I have two different Brooks, a Swift TI and a B17 Pro, and both have been ridden in rain...but I keep them covered with a Velox saddle cover when in rain even though it's likely that the saddles would probably be ok without the covers-I'm probably just anal about it.

Also I don't break my saddles in using Profide as others do, I break them in naturally which takes longer but I feel the results are better...but I could be wrong about that; but I do use it afterwards for sweat and water protection.