British Rail Class 320

The BR Class 320 was a fleet of twenty-two three-car 25 kV AC electric multiple unit sets built at BREL York in 1990, representing the fourth generation of electric multiple units for the Glasgow suburban network and the last to be built on the classic BREL York body platform that had served Scottish suburban electrification since the Class 303 Blue Trains of 1960. Ordered by Strathclyde PTE to expand capacity on the Clyde network as patronage grew and the older Class 303 sets reached the end of their lives, the Class 320 shared the body and mechanical specification of the Class 318 but was built to a slightly updated interior standard reflecting the passenger expectations of the early 1990s.

The twenty-two sets entered service in 1990 at Shields Road depot, Glasgow, and went straight into work on the inner Glasgow suburban services — the Argyle Line through Central Low Level, the North Clyde routes via Queen Street Low Level, and associated services to Airdrie, Motherwell, and the Cathcart Circle. The Class 320's arrival allowed the final withdrawal of the oldest surviving Class 303 Blue Train sets, closing a chapter in Glasgow's electric railway history that had begun thirty years earlier.

Under successive franchise arrangements the Class 320 fleet has been refurbished and updated at various intervals. The sets received interior upgrades broadly similar to those applied to the Class 318 fleet, maintaining their competitiveness alongside newer rolling stock. As of 2026 the entire Class 320 fleet remains in active ScotRail service, approaching thirty-five years old — a longevity that reflects both the durability of the BREL York body and the scale of investment that ScotRail and its predecessors have made in maintaining the fleet. No Class 320 has been withdrawn from service.