LB&SCR E4

The LB&SCR E4 Class was a series of inside-cylinder 0-6-2 radial side-tank locomotives designed by Robert John Billinton and built at Brighton Works from 1897, representing a development of the E3 Class 0-6-2T with a radial trailing axle in place of the bogie for better guidance on the LBSCR's curved suburban and branch lines. The E4 became Billinton's standard heavy suburban and mixed-traffic tank type, built in moderate numbers for the LBSCR's varied requirements across the Sussex network.

The radial trailing axle — a single axle mounted to swivel slightly rather than the full bogie of the E3 — gave the E4 better curve negotiation than a fixed trailing axle while being simpler and lighter than a full bogie. This made the E4 suitable for a wide range of LBSCR secondary and branch duties: the heavier suburban stopping trains, the goods and mixed workings on the Sussex branches, and the coastal resorts' seasonal traffic.

The E4 Class gave long service under the LBSCR, Southern Railway, and British Railways, with some examples lasting until the early 1960s. One example, 32473 Birch Grove, was preserved and now works at the Bluebell Railway in East Sussex — the heritage railway that operates over part of the former LBSCR East Grinstead branch, making it one of the most historically appropriate locations for a preserved LBSCR locomotive.