The British Rail Class 303 electric multiple units, also known as "Blue Train" units, were introduced in 1960 for the electrification of the North Clyde and the Cathcart Circle lines in Strathclyde. They were initially classified as AM3 units before the introduction of the TOPS classification system, and were the dominant EMU on the Glasgow suburban railway network for over 25 years before being progressively phased out by newer rolling stock. The final units were withdrawn from service in 2002. The fleet's lifespan was 42 years.
英铁303型电力动车组被人们称为“蓝色火车”。随着1960年代苏格兰地区North Clyde等电气化线路的开通，303型也开始出现在人们的视野当中。在TOPS分类法出现前，它被称作AM3型动车组。在25年的时间里，此型动车组在格拉斯科附近的郊区铁路网中极为常见。直到2002年，最后一组303型才退役。至此，303型在英国铁路网中服役了42年。