The building of E3137 was begun in August 1965 in the pre-fabrication shop at the British Railways Doncaster works. It was one of the 40 Class A6 (to become Class 86) locomotives built there. The other 60 were built at the Vulcan foundry, Newton-le-Willows. On completion, the future 86259 was sent to Crewe for acceptance tests and then allocated to the AC Lines pool on January 15th 1966, being stabled at the brand new electric depot at Willesden, in North London. Its official Willesdon allocation came in May 1973. In those early years, E3137’s main duties were to be hauling trains from Euston to Manchester and Liverpool.
It was one of several A6s, remaining unmodified, to be renumbered into the 86/0 series and became 86045 on January 9th 1974. The 86/0 fleet was intended for freight work but 86045 was certainly seen on occasional passenger duties. In fact, after just 16 months (on May 21st 1975) 86045 was re-numbered 86259, joining other 86/2s in the main passenger fleet. They received modifications, including flexicoil suspension, resilient SAB wheels and raised gear ratios. By now, the loco had lost its original electric blue paintwork and was turned out in B.R.’s Standard Blue.