Orca, as I recall, British warships in Desert Storm had adequate air cover from our allies, while UK OS and attack assets have seldom needed the kind of protection which you describe, in the post Cold War world. The cahances of needing it within the four year gap left by withdrawal of the SHar? Remote. The chances of an air threat beyond the capability of digi-ASRAAM equipped GR7/9? Even less probable.
We cannot afford to guard against every possible danger - it must be a balance of risks.