The F-4 procurement programme in the 60s/70s might have created the ideal template if it had been carried out a bit more scientifically: buy a decent American airframe, slap in some good British engines, add some British and American/British electronics, hang on some British and other weapons and off you go. You get a decent bit of kit that keeps a substantial chunk of the design and building work in the UK. Sadly, the desire to fit a turbofan engine meant replacing a long, thin, reliable engine with a short, fat, unreliable one. Naturally it didn't fit, and so began a rather sorry and expensive tale. Nevertheless, with the application of a bit more common sense it could have worked, and it might have set a reasonable trend for the future whereby we bought only airframes and kitted them out with homegrown engines and electronics.
I've just spotted T&B's post. Unfortunately things don't seem to work so well in the opposite direction. With both the AV-8B and Hawk acquisition programmes there was a good deal of wailing, gnashing of teeth and debate about why the USN/USMC should buy British designs rather than American ones and both programmes were delayed considerably by political attempts to get them cancelled in favour of 100% American products. I don't think we have quite the same hang-ups anymore.