The Class 37/7 sub-class was created in 1986, with modifications similar to the 37/5s, but with the addition of ballast weights to increase tractive effort. 37701 emerged in its new guise in November of that year. Initially the refurbished locos were repainted in the then current Railfreight grey colour scheme. 37701 is pictured heading for Llanwern with a loaded MGR on 2 July 1990, passing a vintage GWR semaphore signal at East Usk Junction, Newport.