the Ca-class destroyers and Type 81 (Tribal) class frigates from 1955. The Mk 5 twin 40 mm close-in AA batteries like the single 1950s Mk 7/9 40mm L60 Bofors were more effective than Seoond World War 2-pdr "pom pom" or Mk 3 40 mm Bofors and still somewhat useful against first and second generation jets in the 1982 Falklands War indicated but by 1959, were seen as unfashionable and irrelevant to the expected scenarios of missile, standoff and high level attack and , 1959 saw the last fittings of multiple Type 262 radar controlled Mk 5 mounts on and . The refit of Swiftsure was expensively slowed, when the hull was discovered in early 1958 to have compressed more than under the weight of a new bridge, there were many stanchions fitted internally below the new bridge to prevent further collapse of the structure, which was similar to that fitted to Belfast, and intended in both cruisers to allow the fitting of data links to the carriers and an operations room which would have included screens for the new Type 965 radar and Type 184 sonar requested by the RN staff in 1957 for Swiftsure and Superb. However the hull was rebuilt in 1958 and by early 1959 the structural reconstruction was complete but the old armament was assessed as too obsolete to fit. The option of fitting the new 3-inch twin 70 mm turrets in centreline, 'A', 'B', 'X' and 'Y' positions was possible, but converting the ship from DC power to AC for the new guns, added at least another half million pounds to the cost. Slow progress on debugging new 3-inch/70 calibre guns, which saw the aircraft carrier Victorious armed with slower firing US 3-inch/50 calibre mountings. Plans to fit the 3/70 to the Colony class and Swiftsures and Superb were abandoned by 1951. The RN ordered only 25 of the 3/70 auto AA mounts for the Tiger class, Type 41 AA frigates and 17,000 ton GWS gun and missile cruisers which were cancelled in 1957 resulting in the 3/70 stock being sold to the RCN in 1957. The USN ordered 20 3/70 AA turrets using the same ammunition as the RN/RCN mount and the USN actually fitted the gun to USS Norfolk, 4 Mitcher DDL and several Gearing Fram 1 destroyers but found the mounting so difficult they never fired the guns at all while they