I don't think it's about aeroplanes...
...the wrong decision you guys made in the late 60s was the one about leaving the British Commonwealth to join the European Economic Zone, or was it the Common Market (
what did you call it before this more modern pseudo-federation?) That single mistake pretty much changed the course of history from one where Britain was at the middle of everything with friends all over the world, to one where it has become a small group of islands off the west coast of a mainland populated by reformed enemies.