The Thames-class lifeboat was operated by the Royal National Lifeboat Institution (RNLI) from its stations around the coasts of the United Kingdom between 1974 and 1997. Six were ordered but only two completed; they have both been sold on to other users.
In the 1960s the RNLI’s fleet consisted of motor lifeboats of limited speed due to the shape of their hull. The United States Coast Guard (USCG) had developed a faster 44-foot motor lifeboat which planed across the water with a reduced contact area and therefore could move much faster. The RNLI obtained one in 1964. This led to the introduction of the 44-foot-10-inch (13.67 m)Waveney-class into service in 1967. The RNLI’s architects designed a larger version with a longer hull and a bow of different shape. Six boats were ordered, four from Brooke Marine in Lowestoft and two from Richard Dunston in Hessle, but a cash-flow problem saw the project cancelled after just two of the Brooke Marine order had been built. Cancellation charges were paid as the builders had already ordered the necessary materials. Instead the alternative Arun-class lifeboat, which had first launched in 1971, went into full production.