Why Albion and Bulwark lack helicopter hangars

Why do the Albion-class amphibious ships have flight decks but no helicopter hangars?

Their hangar and support deck was deleted to save money on the assumption that a separate helicopter carrier would always accompany them.

Albion and Bulwark were designed with a deck containing a helicopter hangar, larger hospital, and gym. Removing that deck cut cost and left more limited medical and support spaces inside the ships. The decision assumed they would deploy with HMS Ocean or another aviation ship that could provide hangar capacity. When the planned supporting force did not survive later budgets, the amphibious ships retained the consequences of that earlier saving.