The seven actors have had widely differing careers.
Colin Welland went on to write Chariots of Fire
Robin Ellis starred in Poldark
Michael Elphick played a succession of TV hard nuts (some of them lovable)
John Bird is a satirist
Colin Jeavons has been one of TV's most reliable character actors
Helen Mirren is a dame
Janine Duvitski does comedy- usually as some funny male's even funnier sidekick
They are all bloody marvellous. Especially Duvitski.
I don't really subscribe to the view that TV then was better than TV now. But one thing has changed. Back in the day TV had an avant-garde. It's name was Denis Potter. If TV today is less daring and experimental than it was thirty years ago it's because Denis Potter is dead.