I was reminded more of him as Reginald Perrin. Much as I love Leonard Rossiter, I don't think he had the acting range required for this role. Still loved the film, nevertheless.

Concur he was a very good yet underrated actor. He appears in other excellent movies but never was really well-known to the American audience. Barry Lyndon was initially panned by many critics, but over the years has gained a reputation as one of the best and most artistic films ever made.

I like the scene where Quinn flips out in the garden with Nora. Rossiter's Quinn is always on the verge of exploding, but can't do so because he's a giant coward and because he's trapped behind all these prim-and-proper English customs.
So his face becomes a weird warzone of emotional repression. You can almost feel his face wanting to explode.

Absolutely, his 'eyes right' pose and his dancing are stand out for me.
As for Krger, another Fantasic actor. Seen him recently in Flight Of The Phoenix and amongst some great actors he also stood out in his role.

He has the funniest role in the film, I think.
Watching the film again recently, Hardy Krger's (Captain Potzdorf) performance also stood out.
All the actors in the film, though, deliver awesome pregnant pauses. Kubrick begins almost every line of dialgoue with a dramatic long pause. It's amazing how carefully calibrated the line-reading is.