The other choices would be France , USA , or Italy , but these were viewed at the time as very much in the second rank of builders , not so much on the quality of the ships they could produce , rather than the capacity in terms of the number of shipyards capable of building you a dreadnought battleship .
In Britain , more than a dozen .
The German yards could only build about two ships to Britains five , in all types and classes , and were working fairly flat out in the decade leading up to WW1 .
Not so in Britain , where spare capacity remained well into the war .
By the time Agincourt was being ordered the 12 inch twin turrets were being superseeded in the British Navy , and with older pre-dreadnoughts starting to be taken out of commission I suspect that a fair amount of spares , finished items rejected by British admiralty inspectors , and surplus material " kicking about at the back of the yard " could be incorporated into the ship .
( None of this stuff necessarily being particularly defective ) .
As schemed , Agincourt was not intended to lie in the line of battle for sustained action against a first rate foe and perhaps needs to be compared with Minas Gerais / Sao Paulo , Moreno / Rivadavia , Dante Alighieri / Caio Duilio / Conte di Cavour , and Courbet types , as her putative "opponents" .
The fact that the gun system worked well is a tribute to the sound design of the 12 inch twin , perfected long before , and the liking for the gun persisted up to the Washington treaty , where a British proposal to limit all new battleships to 12 inch weapons was made .
Does anyone know if the French style lavatory pans were replaced in a refit , or did the poor British matelots have to carry on squatting ? ( Bloody difficult to maintain your balance while she is pitching her forefoot right out of the water , as in the photo ! I expect there were several tobacco pouches that fell down the 'ole , to cries of " Oh dear me ! " ) ;-0
" Relax ! No-one else is going to be fool enough to be sailing about in this fog ."