In the same year he introduced the first of three important tank engine classes, which were ultimately produced in large numbers. The diminutive LB&SCR A1 Class (Terrier) 0-6-0 tanks were introduced in 1872 and a number were still in active use in the 1960s; several have been preserved. The D1 class 0-4-2T were used for London suburban services of the LBSCR from 1873 until electrification and some survivors lasted until the late 1940s. The last survivor of the E1 class freight 0-6-0T introduced in 1874 was withdrawn in 1962.