I'd read somewhere about an impressive length of disused railway line at a place called La Fregeneda so, today being a bank holiday, we drove up there to have a look.
We found the village OK and, on an information board at the entrance to the village, there was mention of the last 17km stretch of the line from La Fregeneda to the International Bridge on the Duero having 20 tunnels and 13 viaducts and a change in height of some 300 metres. We wandered about trying to find the line and a few kilometres up an unmade road we saw a couple of the viaducts in amongst the hills but we couln't find the track itself despite there, supposedly, being a disused station in the village.
Class 40 was a type of diesel locomotive used by British Rail and presumably by the companies that came after in the UK. I once met a group of lads, members of the 40 Riders Club, whose ambition was to ride a train, at least once, pulled by each of these locos.