The First London Naval Treaty of 1930 extended the "shipbuilding holiday" through to 1937. Planning began again in 1935, drawing on previous design work. The new class would be built up to the Treaty maximum displacement of 35,000 tons. Alternatives with 16-inch, 15-inch and 14-inch main guns were considered and the 15-inch armament was chosen. Most designs were intended to steam at 27 knots with full power, and it was decided that the likely decisive range in a battle would be from 12,000 to 16,000 yards. Armour and torpedo protection formed a much greater portion of the design than that of the previous Royal Navy battleships.