Isn't it a case of rather than looking at current population, it should be looking at further developments and demand?
E.G if Okehampton/Tavistock and it's surrounding area are due to have some housing developments then reopening lines, just like new stations could be beneficial.
It's OK for anyone to say x place is 5 miles away but the reality is that the railways will be used by commuters if it is there at the doorstep. In my case, I live 2 mins from an old station - I would use that line daily had it not been axed but I will not travel three miles to the nearest station to commute.
Sorry, but your claims don't stack up.
What it depends on is where people are commuting to and from and how practical the alternative is.
In its simplest terms you could take Milton Keynes as an example - the vast majority of which is more than 2 miles from the nearest station. Yet because the key destinations are London and Birmingham, for many people driving the 3-5 miles to a station and getting on a train is eminently practical.
To go back to the topic of this - Colne, where are the likely employment centres? Take a look at a map:
Burnley - some will use the train, many won't because of where the stations are in relation to the areas of employment.
Blackburn - probably more attractive to rail commuting given the location of the station.
Northern / North East areas of Manchester - less attractive to use rail because the route in is the long way around via Blackburn and Bolton which would necessitate going into Manchester to come back out again.
Some *might* drive to Skipton, but it's not a major employment centre - more likely are Keighley or Bradford - which Selrap wouldn't address - because Colne - Skipton would take 15-20 mins and Skipton - Keighley another 15 mins. The AA reckon a driving time of 30 mins - so the train wouldn't offer any real advantage.