Class 303 (Pressed Steel ScR Glasgow Suburban Services) AM3

These electric multiple units were introduced for the newly electrified North Clyde and Cathcart Circle lines in Strathclyde. They were later used on other lines in the Glasgow area. The near identical Class 311 was also built later in the 1960s, though by Craven. Together they were known as the Glasgow Blue Trains due to them being in Caledonian Blue livery, though this was replaced by standard BR blue in the 1970s.

AM3 at Westerton [1]

Information
Number built:	273 (91 3-car sets)
Built:	1959-61
Builder:	Pressed Steel
Motor:	4 MV155 traction motors (25kV/6.25kV AC OHLE)
Power:	829 hp (618 kW)
Formation:	DTS (Driving Trailer Second) +MBSO (Motor Brake Second Open) +BDTS (Battery Driving Trailer Second)

The Class 303 was based on the Mark 1 coach and had Metropolitan-Vickers electrical equipment. After some initial teething troubles including an explosion aboard one in 1960 due to an overheating transformer that injured some passengers [2], the Class 303 became the main electric multiple unit in the Glasgow area until the 1980s. Although some withdrawals had already taken place over half of the class were refurbished in the 1980s. Some later were transferred to north west England for awhile. 

However, the Class 303 remained in service in Scotland until the final withdrawal in 2002. One set has been preserved.

[1] Norman Simmons, "Railway review", Airfix Magazine (December 1964) p. 108

[2] Alex Swain, Overhead-line Electric Multiple Units (Ian Allan, 1990) p. 34