Do you have found photos with a gun above the rear 6" casemates?
In
Ships of the World History of British cruisers is a photo of
Essex in 1912-14 (p. 56), which appear to have a 3-pounder there (not bulwarks there!). In the same book is a photo of Cumberland (p. 59) - also without bulwarks there and there appear to be a small gun to the rear of the search light above the rear 6" casemates. But it is difficult to see.
I found somewhere a photo of
Cumberland in 1913 in Malta, which also have a gun there, which could be a 12-pounder. But the photo is very small. Kent in 1914 appear to have no gun there (see
here). There is a search light at the position of the gun on David's model. I also cannot see a gun there on
this early photo of
Cumberland (only perhaps a 3-pounder next to the forward funnel).
The most obvious difference between the ships as completed and in 1914 are probably the spotting tops and the high topmasts. I would expect bigger changes of the armament to have happened latter in First World War.
I have started to built HMS
Monmouth and I would like to depict her in 1914, therefore I am searching for similar information.
Later I would like to built a modified ship, e.g. HMS
Donegal (p. 288 in Friedman) with dazzle pattern and the 6" guns moved to the upper deck.