[5][18] When first conceived in the late 1970s, the Type 23 was intended to be a light anti-submarine frigate with a towed array sonar to counter Soviet nuclear submarines operating in the North Atlantic.

The procurement of the class was announced in the 1981 Defence White Paper as "simpler and cheaper than the Type 22 [with] its characteristics... framed with an eye to the export market as well as Royal Navy needs.

"[19] The ship was designed by the Royal Corps of Naval Constructors, in close partnership with the prime contractor, Yarrow Shipbuilders.

[21][22] Unlike conventional Sea Wolf, the missile is boosted vertically until it clears the ship's superstructure, and then turns to fly directly to the target.

Consequently, the ship's structure does not impose no-fire directions that would delay or inhibit missile firing in a conventionally launched system.

With the addition of Harpoon surface-to-surface missiles and a medium calibre gun for naval gunfire support, the Type 23 had evolved into a more complex and balanced vessel optimised for general warfare, which introduced a host of new technologies and concepts to the Royal Navy.

These included extensive radar cross-section reduction design measures, automation to substantially reduce crew size, a combined diesel-electric and gas (CODLAG) propulsion system providing very quiet running for anti-submarine operations and a large range.

The Government's declared policy for construction contracts for Type 23 was "...competition, the aim being to secure best value for money for the defence budget."

Aside from refurbishment of the mess decks and drive train, the ships are being retrofitted with a transom flap which can add up to one knot (1.9 km/h; 1.2 mph) to the top speed[33] and reduce fuel consumption by 13%, and Intersleek anti-fouling paint which added two knots (3.7 km/h; 2.3 mph) to the top speed of the carrier Ark Royal.

[40] The Chilean Navy is procuring a number of Sonar 2087 towed arrays from Thales Underwater Systems to equip its multipurpose frigates.

On an unspecified date in early 2019, HMS Sutherland tested a modified mounting for the 30mm cannon which incorporated a launcher for five 'Martlet' Lightweight Multirole Missiles, by firing four of them at a small speedboat target at the Aberporth range in Wales.

[citation needed] The intended role of the Martlet is to further extend the Type 23's capabilities against small, fast moving targets beyond the current 30mm, GPMG and Minigun options to provide a long range 'stand-off' ability.

[48] In March 2019, a study commenced for an interim replacement for the ageing Harpoon anti-ship missiles, until completion of the Anglo-French Future Cruise/Anti-Ship Weapon (FC/ASW) programme which was scheduled to enter service in the 2030s.

[citation needed] As of 2021[update], these three ships remain in service with the Chilean Navy and were upgraded by Lockheed Martin Canada by the local ASMAR shipbuilding company.

The remainder are equipped with the Type 2087 Towed Array Sonar, and are primarily tasked with the anti-submarine warfare mission.

[75] In 2021 in a written answer provided to the House of Commons Select Defence Committee, the First Sea Lord, Admiral Tony Radakin, suggested that older frigates of the class would be retained in service longer than anticipated in order to ensure that escort numbers did not fall below 17 ships (6 destroyers and 11 frigates) and start to rise above 19 escorts beginning in 2026.

She also fired star shells into the night sky to illuminate pro-Gaddafi positions to allow NATO aircraft to destroy them.