Basing a much larger modern Royal Navy

Where would the Royal Navy base ships if Britain funded a much larger fleet?

It would expand Portsmouth, Plymouth, and Faslane first, with Merseyside the leading candidate for a later new base.

Portsmouth, Plymouth, and Faslane have enough latent capacity that a large building program would spend years filling them. Overseas sites such as Gibraltar and Cyprus would support deployments rather than replace home basing. If another major base eventually became necessary, Merseyside offers substantial existing maritime infrastructure. The issue would arise only after decades of sustained construction.