Bit of useless info but for a good number of years in the 80’s the heaviest freight train that ran up the West coast mainline past our depot at Milnthorpe was a double headed type 37 loco hauling 30 Ribblesdale Cement tanks which I was told had a 1500ton payload it ran 5 days a week to Coatbridge IIRC and even if you couldn’t see this train you knew it was the double header because the ground rumbled under your feet with the weight plus you could hear the two deisels getting “stuck in” for the first climb up past Oxenholme to Grayrigg then they needed a run at Shap.An empty train of 30 tanks ran back down next morning,obviously they would have had at least 3 sets of tanks on this job but always the same two “Syphons” pulling the sets.These two engines really earned their keep over the years I would think. Cheers Bewick.