Applying King George V-style belt armor to older battleships

Would King George V-style slab armor have made Queen Elizabeth-class upgrades easier if available earlier?

A related arrangement was possible and could have been considered, especially during Warspite's extensive reconstruction.

External belt armour existed before the King George V class, although the arrangement had not developed to the later standard. Adapting it to an older hull was therefore an option. Warspite's extensive reconstruction offered a particularly plausible opportunity to consider it. How that adaptation would have been carried out remains open.