At the end of World War I there was a widespread belief, particularly in Great Britain, that the pre-war naval arms race had been a significant factor in provoking the war. Among the victorious powers there were plans to rebuild or expand their navies, so the prospect of another costly competition in warship construction was both alarming and unwelcome, especially to the economically exhausted British. However, the Royal Navy wished to maintain its position of dominance and so encouraged discussions to limit the growth of navies. Battleships were the main consideration because of their enormous size and cost but cruisers also formed a significant part of these discussions.
In 1919 the British Government proposed that future naval estimates should be based on the assumption that no major war would occur within ten years – the ‘ten year rule’, which was not abandoned until 1932. The British planned an international conference to discuss ‘Pacific and Far Eastern’ affairs, an area of the world that the United States considered as their sphere of influence. The United States therefore proposed a naval limitation conference, to be held in Washington in 1921, invitations being sent to just Great Britain, France, Italy and Japan, although other countries were invited to attend relevant parts of the negotiations. It was not possible to agree a limit on the total tonnage of cruisers for each country but a limit on the size of individual vessels was agreed – a maximum displacement of 10,000 tons with guns no larger than 8 inches in calibre.
A conference held in Geneva in 1927 again attempted to agree a total tonnage but failed. The London Treaty of 1930 defined two different types of cruiser: ‘heavy’ cruisers with guns larger than 6.1 inches and ‘light’ cruisers with guns smaller than 6.1 inches. The total tonnage for each type was also agreed; in the case of Great Britain this was 146,800 tons for ‘heavy’ cruisers and 192,200 tons for ‘light’ cruisers. To comply with this agreement, the number of ‘County’ class cruisers (‘A’ cruisers) to be built was reduced, as was that of their smaller half-sisters, York and Exeter (‘B’ cruisers).
When the Admiralty first started their discussions after World War I regarding the future need for cruisers, it was assumed that the cost of cruisers required for trade protection in distant places would be provided by the relevant colonies, hence the cruisers were initially referred to as ‘Colonial Cruisers’. The thirteen heavy cruisers comprising the resulting ‘County’ class fell into three sub-groups – the Kent class (Berwick, Cornwall, Cumberland, Kent, Suffolk, Australia and Canberra); the London class (Devonshire, London, Shropshire and Sussex); and the Norfolk class (Dorsetshire and Norfolk). As suggested by their names, Australia and Canberra were funded by Australia, the only part of the Empire to fulfil the expectations of the Admiralty.