Agincourt and the qualitative arms-race gamble

Could a one-off 18-inch HMS Agincourt have capped the qualitative battleship race, or would it have triggered a British-American building contest?

It was a gamble. One ship could establish a visible British lead without the provocation of a whole class, but that depended on how American industry and Congress responded.

The proposed 18-inch Agincourt addresses a different competition from the numerical race against Germany. British awareness of American 16-inch development supplies the basis for an interpretation in which one larger-gunned ship establishes a visible technical lead. Building only one could make a congressional campaign for a large response harder to organize than if Britain ordered a whole class. Britain could then retain an image of superiority while continuing to build 15-inch ships. This is a proposed explanation for Agincourt's role, with the risk of American escalation left open.