been much debate over the introduction of stern torpedo tubes on British submarines. The effectiveness of a two-torpedo stern salvo was considered to be doubtful and these tubes would take up valuable space on the submarine. Experience soon led to complaints from British submarine commanders like Commander Anthony Miers (Torbay) about the lack of stern torpedo tubes. Thus, eight of the Group One boats (Taku, Thunderbolt, Tigris, Torbay, Tribune, Trident, Truant, and Tuna) were retrofitted with an eleventh external torpedo tube facing rearwards and this became standard on the Group Two boats onwards. On Group Two boats, the amidships torpedo tubes were also moved aft of the conning tower and reorientated towards the rear. Initially these were angled at 10° off the centerline but this created an area of flat casing that made maintaining depth difficult and for the last two Group Two boats (Traveller and Trooper) and all of the Group Three boats, the angle was reduced to 7°. The primary torpedo used by the T-class submarines was the 21-inch Mark VIII torpedo, principally the Mark VIII** variant. This torpedo weighed with a Torpex warhead and used a Brotherhood burner-cycle engine for a range of at or at . It had a greater propulsive efficiency than any contemporary torpedo of a similar size but shortages of the Mark VIII early in the war led to some submarines using the older Mark IV. The Mark VIII was primarily fitted with a contact pistol, which detonated the torpedo upon impact. A non-contact magnetic pistol known as the CCR (Compensated Coil Rod) was also developed and used during the war. Like the magnetic pistols developed by many other countries, the CCR gave endless trouble and was eventually withdrawn. Due to development problems with British postwar torpedoes, the Mark VIII would remain the standard torpedo used by the T class (and all Royal Navy submarines) until 1971 with the introduction of the Mark 23 wire-guided torpedo. Deck guns All T-class submarines, as built, were fitted with one deck gun as a weapon of surprise and self-defence. This was either the 4 inch QF Mark XII or XXII (both interchangeable) on an S1 mounting. The mounting was located above the casing and forward of the conning tower, with a characteristic breastwork that rotated with the gun to provide room for the crew to operate the gun. No armour or overhead protection for the 4-inch