Vanguard was shaped by wartime time limits

Was HMS Vanguard built exactly as the Royal Navy wanted?

No; she was a wartime compromise shaped by what could be completed with the time and resources available.

War construction rarely permits every desired feature to survive into the completed design. Materials, yard capacity, available weapons, and delivery deadlines force compromises. Vanguard was built around what Britain could achieve in the time available. A completed useful ship can matter more than an ideal design that arrives too late.