Hertfordshire Rail Tour's The Concrete Cow railtour on the 12th January 1985 covered a wide area from Watford Junction, Kensington, Clapham Junction, Neasden, Aylesbury, passing Quainton, Milton Keynes, Oxford, Reading, East Croydon, Clapham Junction and back to Watford. The formation consisted of 4TC's No. 401 and 421. Full details on The Six Bells Junction website - navigate through the railtours menu.