The elevation data from the electronic 1:25000 OS maps also varies a bit from Google Earth. The height at the bottom end of the cottage garden looks like 799ft on the OS map. I would say that the yard around the cottage varies in the region of 805ft to 810ft but the ground around the line seems even higher, around 830ft, which is about 10ft above what I get working from Google Earth.
One thing to remember is that the slope of the hillside from the railway track to Daleside Road by what is shown as "Brick House" on old maps is about 1 in 4. The track from the Depot Cottage to the yard goes up at least 1 in 10 if not steeper.