They were the largest and most heavily armed of the S class and required more men to crew. They were one knot faster on the surface, but two knots slower when submerged. Most of the group were built at the yards of either Scotts, of Greenock or Cammell Laird & Co Limited, of Birkenhead, with a handful being built at Chatham, or by Vickers Armstrongs Ltd, of Barrow-in-Furness. Construction was carried out throughout the war, particularly between 1941 and 1945. Equipped with a greater fuel capacity than their predecessors, they operated much further afield, in the Mediterranean and in the Pacific. There were two distinct subgroups. The first were boats of 842 tons, comprising those ordered under the 1939 War Emergency, 1940 and 1941 Programmes (except Sea Devil and Scotsman), plus Sturdy and Stygian of the 1942 Programme; these carried an external stern torpedo tube in addition to the six bow tubes. The second subgroup were boats of 814 tons, comprising Sea Devil and Scotsman of the 1941 Programme, plus those ordered under the 1942 and 1943 Programmes (except Sturdy and Stygian); these carried no external torpedo tube, but had a thicker welded pressure hull providing for an operational depth limit of - compared with the limit in the first subgroup. Losses continued to be high. Nine ships; P222, Saracen, Sahib, Sickle, Simoom, Splendid, Stonehenge, Stratagem and Syrtis were lost during the war, and Shakespeare and Strongbow were so badly damaged that they were written off and scrapped. Many surviving ships remained in service after the war. Sportsman, by now transferred to the French Navy, was lost off Toulon in 1952 and Sidon was sunk after a torpedo malfunction in 1955. Ships: Five ships were ordered under the 1939 War Emergency Programme. HMS Safari HMS Sahib HMS Saracen HMS Satyr HMS Sceptre Twenty ships were ordered under the 1940 Programme. These differed from the initial five by having an external stern torpedo tube fitted, also a 20 mm Oerlikon AA gun and air warning RDF installed. HMS Seadog HMS Sibyl HMS Sea Rover HMS Seraph HMS Shakespeare HMS P222 which was lost before a name could be allotted to her. HMS Sea Nymph HMS Sickle HMS Simoom HMS Sirdar HMS Spiteful HMS Splendid HMS Sportsman The final seven further ships (P81 to P87) ordered under the 1940 Programme, all from Vickers-Armstrongs, were cancelled during 1943 (and were never laid down