A class of ten ships was envisaged in 1958 for about £6–7.5 million each, equivalent to a costed programme for four large, Seaslug-armed, 15,000-ton cruisers, estimated at £14 million each, based on an upgraded "Minotaur"-class cruiser (1951), approved for full design in early 1955. The final four County-class ships, with hull numbers 07 to 10, were delayed in 1960 while an anti-submarine escort carrier was considered. Hulls 07 and 08 were approved in 1963 as a temporary stopgap, and the ninth and tenth hulls were cancelled.