Cold War defence spending was sufficient to provide armed forces big enough to meet peacetime needs, and a small, cheap, nuclear deterrent which would have bought some negotiating time.
But unscrupulous politicians pretended that our Cold War armed forces were sufficient to fight a major war against the 'Bloc, and therefore encouraged the public to expect a 'Peace Dividend' once the Cold War ended. The opportunity was not taken to trim those capabilities which were no longer relevant, and instead, most of the cuts fell on units which could have had a useful post Cold War role (including many of the FJ units which participated in Granby).
That Genie is now 'out of the bottle' and persuading the general public of the need for higher spending (with a commensurate increase in income tax) looks to be an impossible task.
In fact, properly structured armed forces, capable of meeting all likely post Cold War contingencies (and including at least three full-scale carriers!), would cost much more than the Cold War armed forces did. I'd support such spending personally, but recognise that it ain't going to happen.