Say, the P.1127 project is mismanaged and runs into various glitches and delays. Or it's just cancelled by the 1964 Labour government. Anyway, by mid 1960's, the initial VTOL craze is over and the project is quietly shelved.
Now, what happens to RAF, RN and USMC?
For RAF I'd imagine the replacement would be more traditional aircraft perhaps with focus on Swedish (adopted by the Finnish AF too) style of distributed operations. Versions of Jaquar?
For RN, would Invincible-class become RN Kirov's or Vittorio Veneto's instead? Would there be need to have a longer range Sea Dart?
For USMC?
And, finally, what we all are waiting for, the Falkands might be still winnable or loseable for RN even if there were no Sea Harriers or any Harriers at all.