The Rothesay-class was an improved version of the Whitby-class anti-submarine frigate, with nine Rothesays ordered in the 1954–55 shipbuilding programme for the Royal Navy to supplement the six Whitbys.

Seacat was not yet ready, and Yarmouth was completed with a single L/60 40 mm Bofors mount aft as a temporary anti-aircraft armament.

The main alterations were to build a hangar and flight deck for a Wasp Helicopter and to fit Seacat anti-aircraft missiles.

The recovery instructions were sent from Houston to Halifax, Nova Scotia where the Royal Canadian Navy sent them by Morse Code to the ship.

Luckily the space craft came down amongst a US Navy task force with two aircraft carriers and television cameras in the Pacific Ocean.

Several of Bravyy's crew were washed overboard in the incident with Yarmouth rescuing two of them, although two of the seven Soviet sailors were lost in the accident.

Yarmouth's helicopter flew a doctor over to Esso Chile and ferried the wounded to shore for further medical treatment.

[20] On 28 February 1976, in the course of the Third Cod War, Yarmouth collided with ICGV Baldur's stern, severely damaging the frigate's bow,[21] and forcing her to limp away from the patrol area assisted by the Royal Maritime Auxiliary Service tug Rollicker.

On 4 May, when Sheffield was hit by an Exocet missile, Yarmouth provided anti-submarine protection as Arrow attempted to fight the fire.

On 21 May when Ardent was hit and set on fire by Argentine Skyhawks, Yarmouth rescued the crew of the stricken ship and later transferred them to the SS Canberra.

For the next ten days she continued to act in an air defence role during the battle of San Carlos by day, but by night operated a variety of missions including shore bombardment, anti-submarine patrols, covert operations and escorting merchant ships to and from the landing area.

Yarmouth engaged the coaster with her 4.5" guns west of Lively Island; the Argentine vessel evaded capture by running aground at Seal Cove.

[29] Before leaving South Thule, Yarmouth was refuelled by the RFA Olmeda on 21 June, which may have been the most southerly RAS(L) in the history of the Royal Navy.