I’m sure that at OCTU we were taught to salute on 4 occasions:
1. Any senior officer - which includes the other appointments under the Crown referred to above
2. The Cenotaph.
3. Last respects to the dead.
And
4. Greeting any lady. Witness a scene in “ In which we serve” when Noel Coward ( a Captain RN) greets the new wife of a very junior member of his ship’s company with a salute. And in those days films got that sort of thing right!
And no, never “Thank you”