In 1975, the most interesting prospect for new locomotives was the Ministry of Defence, MOD. For several years they had talked about a replacement programme for their "M" type locos, now it really was going to happen. This was prestige business and competition would be strong. A considerable effort had been made during the previous two years to convince the MOD of the advantages of the Vanguard design well in advance of their enquiry in the hopes of influencing their specification. The strategy paid off and the company was awarded the contract for six locomotives in 1976. These machines proved very suited to the Ministry requirements and three such contracts have now been completed making 18 identical locomotives now in Service.