I've just had a look at that report. I'm sure the consultants know their stuff, but I can't say I agree with all the costings in it - as I understand it, they say a station could be built at Middlewich for £0.6m, and it also seems to allow very little for track upgrades. I would also question the assessment that a Crewe-Northwich shuttle would generate almost as much demand as a through service to Altrincham or Manchester - 200,000 passengers per year is a pretty busy station in the North in 2008 - can that really be achieved with an hourly shuttle not offering connections at Northwich? Hopefully a good case can be out together for Middlewich but I would put the BCR of 5 in the optimistic bracket.
My impression is that the costs are grossly understated and the usership significantly overestimated.