During the mid-to late 1970's a couple of services from Hull to Kings Cross were attached to carriages from Leeds at Doncaster, going forward to the 'Cross together. The Hull portion was marshalled next to the train loco southbound but trailed the Leeds portion northbound from Kings Cross. My question is; which loco worked through to London from Doncaster, was it the loco from Leeds or from Hull?
Any assistance would be very much appreciated.