As a result of poor reliability of the various locomotives used by British Rail to haul stone trains from the West Country (with availability of the Class 56 locomotives from May 1984 as low as 30%, and only 60% of trains running on time), Foster Yeoman began negotiations with British Rail to improve service. Having already supplied its own wagons (with a reliability level of 96%) Foster Yeoman suggested to British Rail that it could operate its own locomotives, which would be the first privately owned engines to run on British rail tracks. British Rail's problem was the hard tie-in and control of the Rail Unions, but nevertheless BR accepted the principle.