I have a feeling that the Anson Class are going to be considerably different in this timeline, they're probably going to be a couple of knots slower and plow all of that freed up displacement into a battleship-scale all-or-nothing armour scheme, which will play havoc with the Washington Treaty negotiations.
what would be the OTL equivalent of this class?
(In my ignorance the only Anson class I recognised is a late Iron Clad)
Perhaps you mean the OTL Admiral Class which in its originally planned form was an Improved Queen Elizabeth battleship?
This would have been 4 ships (including one named Anson)
but the requirement was changed to be a large better armoured BC
(to counter the Mackensens which were mistakenly thought to be armed with 15.2 inch guns
not the 13.8" used to match the British 13.5)
In the end, only Hood was built because the Prussians never actually completed any 15" BC designs