When HMS Warrior might have become a two-deck ironclad

What is the story behind plans for HMS Warrior as a two-deck ironclad?

Britain considered a much larger three-ship response while La Gloire's capabilities were uncertain, then adopted the more economical single-deck Warrior once the threat was understood.

British planners initially did not know how formidable La Gloire would be, so the possible response was three enlarged two-deck ships of roughly ninety guns. Better information suggested that a cheaper and more flexible single-deck Warrior would be sufficient. The larger alternative would have needed a longer and broader hull, at substantially greater expense. Great Eastern, Great Western, and Brunel's other work provide the comparison offered for Britain's ability to build on that scale. La Gloire had already become the first oceangoing ironclad; Warrior's purpose was to surpass the French achievement. Its scale followed an assessment of the rival ship and the intended margin of superiority.