Queen Elizabeth and Revenge begin replacing the 12-inch battle fleet

Were the eight planned Revenge-class super-dreadnoughts intended to replace Britain's older 12-inch-armed ships?

They were the start of that replacement, especially when combined with the six planned Queen Elizabeth-class ships.

The Revenge class began the replacement process, with more work needed beyond a one-for-one exchange. The eight planned Revenge-class ships followed the Queen Elizabeth class. Taken together, the two programs represented fourteen new 15-inch-gun battleships in the theoretical full build. That scale begins pushing the oldest 12-inch-armed ships out of the battle fleet.