The first years of World War II had shown that British destroyers were ill-equipped to deal with concentrated air attacks, and the Royal Navy suffered heavy losses as a result.

The proposed anti-aircraft (AA) armament were eight 40/60 mm guns in twin mountings set atop the middle and after deck houses to give all around, overlapping arcs of fire.

With these parameters accepted, a sketch design was approved in the autumn of 1941 and orders for sixteen ships (two flotillas) were placed under the 1942 programme.

These comprised Barfleur, Trafalgar and St Kitts (with Swan Hunter, Wallsend); Armada, Solebay and Saintes (with Hawthorn Leslie); Camperdown and Finisterre (with Fairfield, Govan); and Hogue and Lagos (with White, Cowes).

These comprised Gabbard (with Swan Hunter); Gravelines and Sluys (with Cammell Laird); and Cadiz, St James and Vigo (with Fairfield, Govan).

Barfleur ran trials in September and was commissioned but had to return to the Tyne to await delivery and fitting of her director and fire control system.

Barfleur was in Tokyo Bay during the Japanese surrender ceremony on 3 September 1945 and after the end of the war she was joined by Armada, Trafalgar, Hogue, Lagos and Camperdown.

A further refinement saw the removal of the depth charge equipment and single 40/60 mm Bofors gun from the quarterdeck, to be replaced by a Squid ahead-throwing depth-charge mortar.

Saintes recommissioned in 1949 when, as D3 and with Armada, Vigo and Gravelines, they replaced Troubridge and the V class as the 3rd Destroyer Flotilla, Mediterranean Fleet.

The following year Saintes having finished her major refit at Rosyth resumed command of the 3rd Squadron, relieving Barfleur in the Mediterranean.

Her AA armament now consisted of four single 40/60 mm guns and a quadruple Sea Cat missile launcher on the after end of a new deckhouse which stretched from just aft of the funnel to the quarterdeck.

Here she was used as the training ship for Artificer Apprentices from HMS Caledonia who kept her engines and machinery in full working order.

She was eventually replaced by the frigate Duncan in 1972 and she too headed for the breakers yard at Cairn Ryan, the last of the Royal Navy's 1942 Battle class destroyers.

These turrets offered improved ammunition handling and a faster rate of fire due to their semi-automatic breech action and it was thought that this was sufficient to preclude the fitting of the single gun amidships.

The bridge structure was raised as earlier trials in Saintes had noted that the higher profile of the Mk VI turret obstructed visibility forward.

Six were ordered on 10 March 1943, with names commemorating land, as well as sea, battles: Agincourt and Alamein (from Hawthorn Leslie); Aisne and Albuera (from Vickers, Tyne); and Barrosa and Matapan (from John Brown, Clydebank).

Fifteen ships were ordered on 24 March 1943:Corunna, Oudenarde and River Plate (from Swan Hunter); Dunkirk, (original) Malplaquet and St Lucia (from Stephen); Belle Isle and Omdurman (from Fairfield); Jutland, Mons and Poictiers (from Hawthorn Leslie; Poictiers is the spelling used for Poitiers at the time of the battle); and Namur, Navarino, San Domingo and Somme (from Cammell Laird).

Five ships were ordered on 5 June 1943: Talavera and Trincomalee (from John Brown); Waterloo and Ypres (from Fairfield); and Vimiera (from Cammell Laird).

As a result, seven ships, Mons, Omdurman, Somme, River Plate, St. Lucia, San Domingo and Waterloo, were broken up on the slipway.

The two extended ships, Vimiera and Ypres were not scrapped at this time but eventually became a part of the Daring class, programme authorised in 1946.

It was originally intended that all eight ships would form the 4th Destroyer Flotilla, but by 1947 the post-war manning crisis had reached its peak and so Alamein, Barrosa, Corunna and Matapan went into reserve.

Consisting of Agincourt, Aisne, Jutland and Corunna and converted to General Service Commissions the squadron deployed between the Home and Mediterranean Fleets for the next few years.

Led by the 1942 Battle Trafalgar, the squadron completed two General Service Home / Mediterranean Fleet deployments before Jutland paid off into reserve in 1961.

In 1955 a decision was made to convert four Battle class ships to Fast Air Detection Escorts, although the work was not started until 1959.

All torpedo tubes and light AA armament were removed and a large deckhouse containing generators and radar offices was built abaft the funnel.

Each escort squadron comprised a mix of ships of varying type in order to provide an increased capability within each group.

Agincourt spent four and a half years rotating between Home and Mediterranean waters, first as part of the 5th DS and then, after the reorganisation into Escort Squadrons, with 23ES and 27ES.

The decision to run down the carrier fleet, together with the withdrawal of British forces from the Far East, reduced the need for fast air direction ships.

Moreover, the general purpose frigates then being built, such as the Leander class, were fitted with Type 965 radar and modern operations rooms, so they could replace the converted 'Battles' in most circumstances.

She was stripped of all armament and the forecastle deck was extended right to the stern to provide increased space to accommodate scientists and trials equipment, plus a large Sick Bay.