The British Rail Class 31, also known as Brush Type 2 are diesel locomotives built by Brush Traction between 1957 and 1962 as part of British Railways’ modernisatio place. Originally fitted with Mirrlees engines, as considered Class 30s, they were later re-engined with English Electric units due to performance issues. Initially intended for the Eastern Region, they were later used widely across the UK. Sub-classes include 31/0 (with Red Circle electro-magnetic control equipment), 31/1 (standard type), 31/4 (ETH-equipped), 31/5 (ETH removed for departmental use), and 31/6 (wired for ETH but without supply). These locomotives were used for a variety of passenger and freight duties and remained in service for decades across multiple regions.