I was wondering what the record is for the greatest variety of stock used on any one tube or sub-surface line on London Underground has ever been? I can think of an instance of three different stock times on the same line during a fleet transition, but wondering if there are more interesting /complex examples? Northern Line late 1990s: 1959 / 1972 / 1995 stock Just to clarify - I know how good forum members are at finding loopholes! - I’m only interested in stock that operates the timetabled service on the LU line itself. So quoting 416 and 313 units on the Bakerloo line wouldn’t count, nor A or D stock on the Circle line.