They are based on the Dutch-Spanish Royal Schelde Enforcer design, and replaced the Round Table-class logistics ships.

Construction work started in 2002, but saw major delays and cost overruns, particularly at Swan Hunter's shipyard.

The Bay class was designed as a replacement for the five Round Table-class logistics ships operated by the RFA.

[6] After the first Round Table returned to service two years late and after excessive cost, the Ministry of Defence began to investigate the acquisition of new ships.

[5] Swan Hunter struggled to manage the project and contain costs; only 7% of the design drawings were provided on time and more than 52% were over a year late.

[7] The extent of the problems only came to light in September 2003, when Swan Hunter said they could not fulfill the contract at the agreed price.

[6] The design is based on the Royal Schelde Enforcer, a joint project between the Dutch and Spanish resulting in the Rotterdam-class and Galicia-class amphibious warfare ships.

[5] The ships were designed to receive an armament of two Phalanx CIWS, two manual 30 mm DS30B cannon and various small arms, but the exact weapons fit varies within the class.

[14] As a sealift ship, each Bay-class vessel is capable of carrying up to 24 Challenger 2 tanks or 150 light trucks in 1,150 linear metres of space, with stern- and side-ramp access to the vehicle deck.

[15] During the deployment, the ship visited ports across the Caribbean islands and the United States mainland, and intercepted a 575-kilogram (1,268 lb) cocaine shipment.

[16] On 3 February 2010, Largs Bay headed to Haiti with aid supplies for relief efforts after the earthquake.

[19] In December 2010, it was announced that a Bay-class vessel, later identified as Largs Bay, would be decommissioned in April 2011 as part of the Strategic Defence and Security Review.

[27] With no spares available, the need to order from the manufacturer combined with the decision to replace all of the transformers aboard meant that Choules was kept out of service until April 2013.

[28][29][30] In June 2011, Cardigan Bay headed to Yemen to aid with the potential evacuation of British citizens affected by the ongoing unrest there.