the last one I remember meeting was the boss of 204 Sqn at Ballykelly on 1967/68? - O.G. Williams. A nice, if slightly old fashioned, chap. So I have no doubt there were others still floating about at that time.
A little later there was a senior officer at one of the nav schools who still wore the Observer brevet (quite unofficially I am sure). It may be recalled that the 'O' brevet was often referred to "the flying a---hole" and it was generally agreed that the description was very appropriate in his case.
The navy of course has to be different - their navs are still called observers, I believe. Also in the navy a pilot is someone who tries to prevent the captain steering his ship onto the rocks - with varying degrees of success
