Scale 1:48. Plan shows the sectional elevation, a plan of the superstructure, an plan view and a section of the Twin Screw Submarine Design No. 668 (1914) (not built). The section is through the conning tower looking aft. A note in red ink on the plan reads "SO49/14 Approved not to proceed further with this design but when Messrs Vickers are asked to tender for the New Admiralty E's (1914-15), they should be given the opportunity of tendering for their design as well". A Vickers Limited stamp dated 20 January 1914 is present on the drawing. The drawing also bears the signature of the Chief Constructor at Vickers Ltd. There is a tear on the left hand edge.