When British 10-inch guns were a useful choice

How useful were the Royal Navy's 10-inch-armed pre-dreadnoughts and armoured cruisers?

They were useful in their own period, when a 10-inch gun could be the largest practical weapon available.

The ships are judged against the guns that could be built when they were designed. At some points, 10 inches was the largest viable choice. Their usefulness should therefore be assessed within that technical setting.