Haha yeah I know a lot of Australian and Scottish actors can speak received pronunciation and it's largely used in theatre plays because of it's great clarity.
So it makes sense why Leo McKern and Ian Richardson both spoke that way as they did a lot of theatre work and there probably wouldn't of been that much work for actors who could only speak with Australian and Scottish accents.
No idea what John Hillerman's story was though as I only knew him from Magnum PI and yeah I would of just assumed he was another Shakespearean type theatre actor.
A couple of people who caught me out though is David Tennant, I had no idea he was Scottish and slightly off beat James Doohan who played Scotty in Star Trek, like who would of thought he wasn't Scottish?😅 乂º◡º乂
