They have dropped an extraordinary clanger in their selection of warships supposedly illustrating pre war Dover. The one on the Admiralty Pier, over the top of the naval officer's uniform hat, is a brand new Japanese light aircraft carrier. For all their vaunted attention to period authenticity, this is akin to having a line of pre war British motorcars punctuated by a gleaming Toyota Land Cruiser!
The Japanese actually refer to the two ships completed so far as helictopter carrying destroyers. They are about the size of our Invincible class light aircraft carriers which were known as through deck cruisers for years to confuse our dozy MP's. The Japs are building two more much larger ones as shown below, also called destroyers. Theoretically, their constitution forbids them from building aircraft carriers after their shenanigans in WW2.