(Could we pass lightly over ulterior motives {Wilson as Red stooge or worse; TPs with career agendas; Benn in any context}. In the Committee-haggles that decide such things as Defence/Procurement Policy, consensus emerges around a least worst option. No conspiracies).
So, it's January,1968 and Cabinet decides to let India, Malaysia &tc. face up to sovereign Defence Budgets. UK will do Luneberge Heide, Bodo, Akrotiri, SSBN, N.Atlantic, and bits of colonial baggage. Quite enough. Onway was a pile of good kit largely on fixed price/deferred terms from US. Overwhelming logic was to inter-operate (=mercenary crew) with US everywhere, and just add F-newest every few years to the never-never $ invoice. Some UK jobs in inventory ownership: repair much, make little (some licence build if quantities are there - say ATM), because Economics favour US volume. Put UK engineering industry someplace US can't catch us: say sensible autos.
What Healey/Wilson actually did was invest vast resources into UK Defence, favouring Aero. Chevaline, Jaguar, Tornado, 26 new to add to 65 ex-RN Buccs for RAF, Hawk, Seawolf, Rapier, a UK-solo NDB, 8xT.21 Amazon, DDG 14xT.42 Sheffield...and on...and on...all initiated/continued despite the Nation being broke. Before 1971 kids could leave school at 15 and most did: only in 1970 did Education at last overtake Defence's share of GDP (5.1% cf. 4.8%). They did all that because they knew quite as much about the Red Threat as did anyone, and they did their best to gird...affordably. That Threat went away in 1990 because Reds did not know how much was enough, and spent their regime to death.
I would have chopped Puma post-AFVG and bought whatever USArmy/Germany had. Leave the rest alone.