The four british battleships approved under the FY 1910 estimates became the King George V class. They were originally to become repeat Orions, then proto-Iron Dukes; in the end, they turned out something in between. They abandoned the weird foremast arrangement of the Orions in favour of a pole mast stepped in front of the forefunnel, giving them a foretop platform you could actually use; they were however the last british battleships with 102mm secondaries, 152mm ones being considered but not fitted to keep displacement and cost under control.
Although this class was supposed to receive fire control directors for the first time in British warship design, the class ship HMS King George V differed from the others by having a foremast layout that did not allow to mount a director straight away. When she joined the fleet in November 1912, she was painted in a very dark shade of gray (a source called it charcoal gray) that seems to have been standard for home-based British warships in the last years before the first world war.
HMS Centurion's mast was fitted for, but not with a director when completed. She further differed from all her sisters by having a different searchlight layout.
The other two units of the class were - as far as I can tell anyway - virtually identical and impossible to tell apart. HMS Ajax received the main artillery director from the start, but its weight caused the foremast to vibrate in an alarming way, so she received struts to strenghten it. These were attached relatively low, only halfway up the mast, but seemed to have worked.
HMS Audacious looked exactly like Ajax; photographic evidence however indicates that she was already painted in 'battleship gray', a much lighter shade than was usual pre-war, but still darker than the contemporary German paintjob, which became standard late in 1914 (according to one source, not because the dark shade did not work camouflage-wise, but because the pigments to make it were running low). She was the first British battleship loss during the first world war, hitting a single mine off North Ireland and slowly sinking despite intense efforts to save her.
The above drawings represent what I was able to find out about these ships in their initial guise; whoever knows more, please dump it on me.
Later modifications will be shown on this thread as well. But although I think I know quite well what alterations they received during their service, I mostly could not pinpoint when exactly the modifications were made (especially when exactly the masts were shortened and the torpedo nets landed). Anyone with firm knowledge about these matters please step forward, so I can represent their later fit as faithfully as possible. The same goes for the exact hue of the pre-war very dark gray; the one shown here is only an educated guess.