When a cruiser response becomes a capital-ship program

Why would Britain wait before answering Deutschland with new capital ships, and what gun calibre would it choose?

Foreign 12-inch replies would provide a treaty argument for restarting capital-ship construction; in the 1931 setting, 16-inch guns are proposed.

The follow-up asks why Britain would not simply build battleships under the cruiser label. The proposed sequence is to answer Deutschland with 9.2-inch cruisers, then wait for American or Japanese 12-inch replies. Those ships would provide the justification for restarting British capital-ship construction. With Deutschland's launch placing the scenario in 1931, 16-inch guns are proposed for the British fast battleships or fully armored battlecruisers.