From the F3 concept to Vanguard's battlecruiser lineage

What turned the Royal Navy away from updating the F3 design, and how does Vanguard fit the resulting categories?

War plans favored all-round fast battleships, while Vanguard retained a fully armoured battlecruiser lineage in layout and contemporary terminology.

The interwar fighting requirement favored fast battleships with all-round firepower rather than an updated all-forward F3 arrangement. Vanguard is distinguished here from the King George V and Lion fast battleships because contemporary design language called her a fully armoured battlecruiser. That judgment rests on subdivision and a lineage closer to a modernized Tiger than to a faster battleship. Speed, armor, and firepower together provide options, whereas a design built around speed and firepower becomes fragile when either advantage is lost.