Built to the limitations of the Washington Naval Treaty of 1922, Nelson class battleships HMS Nelson and HMS Rodney were unique in being the only battleships in the world with all main batteries mounted on the foredeck as well as being the only European battleships armed with 16 inch guns.
HMS Nelson during gunnery trials. Photo courtesy Imperial War Museum
In order to meet the restrictions something had to give. Hence Nelson and Rodney were given far less engine power than they needed and the ships were slow, their maximum speed being 23 knots vs King George V class battleships laid down in mid 1930s without treaty restrictions which could make 28 knots plus. KGV class had 14 inch guns. The Bismarck carried 15 inch guns as did HMS Hood and the other Royal Navy battlecruisers HMS Repulse and HMS Renown.
In spite of their efforts, the Admiralty had a difficult time making a workable design of the Nelson class battleships. One problem: if all main batteries were trained abaft the bridge structure and fired, then the explosive shock shattered the glass on the bridge.
You can see how massive these ships were even in their truncated state since they had the deck space required for a game of deck hockey, a popular sport in the Royal Navy of the era.