I cannot understand why the MoD allowed the Mark 2 Sea Harrier programme to proceed at the same time but independently of the Harrier II, which became the GR5/7/9. Surely common sense dictates that a coherent policy for UK Harrier projects in the 1980's would have been to have a common airframe based on the more advanced Harrier II structure and aerodynamics, but with avionics suited the seperate requirements of each service. It seems crazy to have spent money putting an advanced radar into a 1960's airframe. To put it in perspective, the AV-8B+ entered service in the same year as the FA2.
Maybe the RN thought it politically better to be deliberately seperate from the RAF project. If they did, not only was it a waste a taxpayers money, but it has proved to be a flawed policy. I suspect that a Sea Harrier II+ would still be in service today as an FAA aircraft.