British increases in gun calibre are described as often proceeding in 1.5-inch steps. The 15-inch/42 is connected with development from the 13.5-inch weapon, while the 16.5-inch/45 is described as a separate barrel project. Work associated with the larger project is then linked to technology for a 15-inch/50. Alternative armaments for the Queen Elizabeth and Admiral classes are considered within that discussion. The larger calibres belong to development proposals and counterfactual outcomes, not the ships' historical fitted armament.
Notable Point · 1:36:55-1:38:02
The 16.5-inch project and alternative British gun development
The discussion distinguishes the historical 15-inch gun from a separate 16.5-inch development project.