British Rail Class 165 Networker Turbo

The BR Class 165 Networker Turbo was a fleet of seventy-six two- and three-car DMU sets built between 1990 and 1992 at BREL York (later ABB Transportation) for Network SouthEast's Thames Valley and Chiltern main-line services. The Class 165 was part of the Networker family that BR commissioned in the late 1980s for suburban and outer-suburban services radiating from London, representing a step forward from both the ageing first-generation DMUs and the locomotive-hauled coaching stock that still worked many NSE routes at the time.

The sets were designed around Perkins 2006-TWH diesel engines, each producing 260 hp, giving a two-car set 520 hp and a maximum speed of 90 mph. The body was built to the wider Networker profile — 2.82 metres, broader than the Sprinter family — giving a more spacious interior with three-abreast seating in standard class and better accessibility than earlier DMU designs. The interior specification was notably higher than the contemporary Class 156 or Class 158, reflecting the NSE premium on presentation for commuter and outer-suburban passengers.

The Class 165 fleet was split between two allocations from the outset: the 165/0 subclass (three-car sets, 165001–165039) for Thames Valley services out of London Paddington to Oxford, Newbury, and Bedwyn; and the 165/1 subclass (two-car sets, 165101–165137) for Chiltern main-line services out of London Marylebone. Under privatisation the Thames Valley sets passed to First Great Western and subsequently Great Western Railway; the Chiltern sets passed to Chiltern Railways, where they continue to work alongside the Class 168 Clubmans on Marylebone–Birmingham and associated services. As of 2026, the majority of the Class 165 fleet remains in service.