Salisbury Class Aircraft Direction Frigates (Type 61)

In the final years of the Second World War and the immediately post war years, studies identified the need for a common design of future frigate that would share the same basic hull and machinery design but could be adapted to suit various tasks: anti submarine warfare (ASW), aircraft direction (AD) and anti-aircraft (AA). This common hull would be built in pre-fabricated, all welded sections. In the event of a nuclear war, this would allow for quick assembly as the prefabricated sections could be transported to different shipyards around the country. A further advantage was the basic hull could be laid down and decision on the specific role could be made later in the construction process. Hence this design was both flexible and cost effective.

The aircraft direction variant, known as the Type 61, was designed to counter hostile aircraft by sailing ahead of a fleet or convoy to give early warning of an aircraft attack. They would then direct carrier or shore based aircraft towards the hostile target or engage the target themselves. For this they would be equipped with a range of radar, electronics and communication equipment and appropriate weaponry to provide limited, close range air defence. The principle differences between the Type 61 and the anti-aircraft variant, the Type 41 (Leopard Class), was that instead of a 4.5 inch turret aft, the Type 61 would have an Type 982 air search radar and an enlarged operations room.

When the Type 61 was in development no appropriate steam plant was available and it was feared this type of propulsion could be unsuitable in a crisis or conflict situation. As speed was not as essential as it was with the anti submarine variant, it was decided to use a diesel plant instead. These were designed by the Admiralty and built by Chatham Dockyard and the Type 61 frigates became the first major Royal Navy warships to be powered exclusively by diesels

The Type 61 frigates were designed with a displacement of 1,738 tons but this increased to 2,170 tons whilst they were under construction due to modifications and alterations. They measured 340ft in length, 40ft in beam and over 15ft in draught. Armament consisted of two 4.5 inch guns, two 40mm anti-aircraft guns and squid anti-submarine mortars. They had a speed of 24 knots and their complement varied in size between 207 and 237

The drawings for the Type 61 were approved in September 1950 and the first four vessels were ordered on June 28th 1951 and bore the names of Cathedral Cities: Salisbury, Chichester, Llandaff and Lincoln. Salisbury, the lead ship, was laid down on January 1st 1952 and was the first post war frigate built for the Royal Navy. Three further units named Exeter, Coventry and Gloucester were ordered under the 1956-1957 estimates from Fairfied Shipbuilding & Engineering Co, Vickers Armstrong and HM Dockyard Portsmouth, respectively..

The four ships of the Salisbury Class served world wide participating in the Beira Patrol, 'Cod Wars' and as guard ships at Hong Kong and Gibraltar. Although Lincoln and Salisbury were fitted with Seacat in the late 1960s, in later years the class became obsolete. Firstly, they were too slow to keep up with the aircraft carriers and other frigates. Whilst the Salisbury Class could only reach 24 knots, the Leander Class could travel at 30 knots as could the aircraft carriers Eagle and Ark Royal. Secondly their principle weaponry of anti-aircraft guns compared unfavourably with newer frigates and destroyers entering service with more sophisticated armaments, notably guided missiles. Consequently after relatively short careers with the Royal Navy, two vessels were sold for scrap, one was sold for service overseas and one was used in a training role before being sunk as a target.