>>9917709the British were a little late on the draw on superimposed turrets, the Americans implemented them before Dreadnought was even designed or laid down but Jacky Fisher (head of the Royal Navy) wanted her built ASAP, so she was laid down after the first American dreadnoughts (pic related) but commissioned before the American ships were.
superimposed turrets saved on weight and were overall less expensive but required more work (building up the turret barbettes above the deck, and ensuring the ship wasn't too topheavy with guns further above the waterline than normal), and since they were a new innovation there were questions as to whether they would ultimately be possible or effective. Fisher was running a tight ship (pun intended) and was in the middle of an arms race with the Germans so he wanted shit completed as quickly as possible, and opted for the more awkward but quicker method of tandem turrets plus several guns on the wings.
wasn't until a few ship classes later (the Orion-class) that the British finally adopted superimposed main guns, after seeing that the American dreadnoughts were successful and superimposed turrets didn't have any real drawbacks.
