Funnily enough I saw the exact opposite occur on Saturday. The w/b service started off (on time) and the e/b service rolled in after a gap (just a bit late). I am doubtful whether the line cleared before the w/b had to pull up (but there again I didn't see that, it might have been OK).
It must save fuel if the w/b gets a good run at Honiton Bank, I would think. Of course, coming the other way from Honiton, it's the same height that has to be dragged up to, and not much of a run up there either.