
In 1950 RENFE - Red Nacional de los Ferrocarriles Españoles, the Sapnish national railway operator - signed a contract with English Electric for the supply of 20 complete 3000vDC locomotives - an order later changed to one for 60 in total. The locomotives, then the most powerful constructed in the UK, were built by EE and the Vulcan Foundry and became RENFE's class 277. The order was noteworthy at the time as it was one that marked the beginning of the ex-Allies economic ostracisation of the Franco regime that had been in place since the end of WW2.
The locomotives were intended for use on the Ujo to Busdongo section of the Oviedo - Leon - Ponferrada railway that was electrified at 3000vDC and had been part of the old Norte railway. Heavily graded and wirth numerous sharp curvatures the line through the Cantabrian Mountains was important for freight, especially mineral traffic, as well as passenger traffic.