An expanded prewar Royal Navy could use a Tiger as a testbed

If Britain built fourteen 13.5-inch battleships and five 13.5-inch battlecruisers before the First World War, would an extra Iron Duke become a testbed?

Possibly, although one of the two Tigers could be chosen instead; the navy would probably need only one dedicated experimental ship.

The proposed programme gives Britain fourteen 13.5-inch battleships and five 13.5-inch battlecruisers before the First World War. With the historical 15-inch building programme added, this would increase the Royal Navy's firepower and leave more ships that the Admiralty could argue remained useful after 1918. Retaining the extra ships could strengthen British demands for greater treaty tonnage and more battlecruisers. The navy would probably need only one testbed. One of the two Tigers could fill that role, since the answer treats their hulls as newer than the Iron Dukes, but the choice remains tentative.