Why Queen Elizabeth rebuilds beat replacement battleships

Why rebuild the Queen Elizabeth class instead of replacing it with new battleships using the old guns?

Rebuilding was cheaper, and Britain lacked the armour-plate production capacity needed for large new battleships at the start of the war.

Rebuilding the Queen Elizabeth class cost less than building replacement battleships, even if a paper design could make attractive use of existing guns. Britain also entered the Second World War with armour plate as a major production bottleneck after the treaty-era contraction of heavy industrial capacity. A fleet plan has to be judged against what industry can actually deliver, not merely the neatest drawing.