the british rail class 485 (or 4vec) and british rail class 486 (or 3tis) electrical multiple units were originally built for the london electric railway from 1923-31 as their 'standard' tube stock. they were purchased by british rail in 1967 and transported to the isle of wight to work 'mainline' services on the newly electrified ryde to shanklin line. at the time the units had already worked for over forty years on the london underground, but their introduction allowed the final steam locomotives on the line to be withdrawn.