As many passengers travel daily on London Underground as the rest of the British railway network in its entirety and passengers will be familiar with the differences between the Underground lines. What perhaps is less obvious to the travelling public is the difference between the sub-surface stock and the much smaller deep-level tube stock which is constrained by the size of the tunnels. Even within these two main types of stock there are differences between individual lines, depending on density of traffic in central London or the suburbs, special demands of servicing Heathrow airport (the Piccadilly Line) and even differing lengths of platforms. Stock on the Underground generally has a long life - the earliest stock is the 'A' stock from the early 1960s still to be seen on the Metropolitan and East London Lines and the earliest tube stock still in operation dates from the opening of the Victoria Line 1967. The most recent is the 1995 Northern Line stock and the 1996 Jubilee Line stock. The introduction to the book gives a historical description of each of the six main types of sub-surface stock and three types of deep level tube stock in operation on the Underground today and is accompanied by detailed specifications of each type of stock and photographs. The book then provides a complete listing of the stock numbers of each vehicle operating on the Underground lines as well as battery locomotives and maintenance vehicles, with the listing grouped under the individual Underground lines, again accompanied by photographs.