During the war, they operated in home waters, particularly the English Channel, and off the Scandinavian coast.

The later second and third groups of S-class submarines would have their fuel capacity expanded to allow them to operate further and overcome this limitation.

Construction was divided between Chatham Dockyard, and the yards of Scotts, of Greenock and Cammell Laird & Co Limited, of Birkenhead.

During the war, they, like the submarines of the first group, mostly operated in home waters, ranging as far afield as the Bay of Biscay and the Scandinavian coast.

One, HMS Sunfish, was assigned to the Soviet Navy (named V-1) and was sunk by friendly aircraft on the transfer route from Dundee to Murmansk.

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 350 feet (110 m) - compared with the 300 feet (91 m) limit in the first subgroup.

Nine boats; 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.

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.