The British Rail Class 28 ( Metropolitan-Vickers Type 2 ) diesel locomotives , or ` Metrovicks ' as they were popularly known , were built as part of the British Railways Modernisation plan . The British Rail Class 28 ( Metropolitan-Vickers Type 2 ) diesel locomotives , or ` Metrovicks ' as they were popularly known , were built as part of the British Railways 1955 Modernisation Plan .