The London, Brighton and South Coast Railway E3 Class were 0-6-2T side tank steam locomotives. One prototype was designed by William Stroudley shortly before his death, but was completed by R. J. Billinton, who later built sixteen further locomotives.
In the summer of 1889 Stroudley designed a class of 0-6-2 radial tanks to replace his earlier E1 class 0-6-0T for short-distance goods and shunting duties. One locomotive was under construction at the time of his death in the December of that year. Intermittent progress on this locomotive was made until August 1891 when Stroudley's successor, R. J. Billinton ordered that further work be delayed whilst he made detailed modifications. This prototype locomotive, No. 158 West Brighton, appeared in traffic on 27th October 1891. The new locomotive was originally classified as F class.
Once the teething troubles had been rectified, Billinton ordered a further sixteen locomotives to a broadly similar design but with increased boiler pressure. These were originally classified 'E-special' and entered traffic between November 1894 and December 1895. All were rebuilt with new boilers and extended smokeboxes from 1918 and some had increased boiler pressure.
The London, Brighton and South Coast Railway (LB&SCR; known also as "the Brighton line", "the Brighton Railway" or the Brighton) was a railway company in the United Kingdom from 1846 to 1922. Its territory formed a rough triangle, with London at its apex, practically the whole coastline of Sussex as its base, and a large part of Surrey. It was bounded on its western side by the London and South Western Railway (L&SWR), which provided an alternative route to Portsmouth. On its eastern side the LB&SCR was bounded by the South Eastern Railway (SER) – later one component of the South Eastern and Chatham Railway (SE&CR) – which provided an alternative route to Bexhill, St Leonards-on-Sea, and Hastings. The LB&SCR had the most direct routes from London to the south coast seaside resorts of Brighton, Eastbourne, Worthing, Littlehampton and Bognor Regis, and to the ports of Newhaven and Shoreham-by-Sea. It served the inland towns/cities of Chichester, Horsham, East Grinstead and Lewes, and jointly served Croydon, Tunbridge Wells, Dorking and Guildford. At the London end was a complicated suburban and outer-suburban network of lines emanating from London Bridge and Victoria, and shared interests in two cross-London lines.