Delighted with the success of the E Class submarines, the Admiralty decided, in 1916, to revert to the saddle tank type of construction, but incorporating the lessons learned from war experience. Two submarines to a new Admiralty design were ordered from Vickers in February 1916 and, being practically elongated Es, they were called E57 and E58. However, overall improvements so distinguished the design that a new class title was adopted, the L Class, and the two boats were later renamed L1 and L2.