What could trigger a British large-cruiser program

Under what circumstances would the Royal Navy actually build an Alaska-style large cruiser?

Either to match American and Japanese ships before a delayed war or to answer a large postwar Soviet cruiser program.

Two strategic paths might lead Britain to build a large cruiser. If the Second World War were delayed until 1945, American Alaska-class and Japanese construction could provoke a British counterpart before the conflict. In a postwar setting, a major Soviet cruiser program could create the same pressure. The design would therefore answer foreign fleet development and status competition rather than meet a need present in every plausible 1940s fleet.