After skipton (towards Keighley) there are overhead power lines, so I would think between Skipton and Hellifield is your best bet for a clear shot.....saying that, there is possibly a good point between skipton and keighley here -
http://maps.google.co.uk/maps?f=q&s...008964&spn=0.002218,0.004823&t=h&z=18&iwloc=A - I think there is a pedestrian crossing over the line (and you can park next to the line)...could give you some low level stuff.
Have just thought of a few more locations between skipton and hellifield:
http://maps.google.co.uk/maps?f=q&s...56306,-2.04115&spn=0.004432,0.009645&t=h&z=17

On the bridge there you would get it coming around a fairly tight corner, but you are pretty high up, also a bit of a walk from the layby further down the road (busy road!)
http://maps.google.co.uk/maps?f=q&s...8415,-2.028203&spn=0.001108,0.002411&t=h&z=19

Not a very pretty view, and if the train is coming from hellifield it will be facing the opposite way to that one, so would need to shoot from the other side, and don't know what it is like that side (doesn't look pretty on the map)