60051 Mary Somerville passes South Moreton with the 6B23 13:12 Colnbrook to Waterston oil empties on 21 June 1991, ironically exactly one month after it failed on the same train and had to be rescued by 37372! At this time Class 60s were still being constructed and this working was generally the only chance of seeing one in the Thames Valley. After the mass introduction of Class 66s, the heavy haulage Class 60s would gain a cult following, but at this time this was definitely not the case, especially when they replaced pairs of 37s on workings such as this!