Crime comedy or crime parody possibly from the 70’s, but it’s hard to tell

I saw this movie when I was a child in the 90’s I believe. It’s most probably british, and it takes place in a mansion where mysterious murders happen. Some of the scene from my memories:
– Beginning of the movie, there are three characters, two of them male, one of them wears round shape glasses, and the other is thin, and maybe redhead. In my mind, the latter is very similar to the actor who played the CIA agent in the Indiana Jones and the Raider of the lost Ark, not the fat one, but the other. I don’t remember the woman. So there is this scene, they are walking on a square and talking with each other. A huge stone pile just falls down in front of them, almost kills them, but they are acting like nothing happened, and step over the pile. Only after a few seconds they turn back and look at the pile.
– Maybe still on the first third of the runtime, they show their room, and there are paintings on the wall, usually portres. The camera shows, that behind the paintings, there is a secret tunnel, and one can open the “eyes” of these paintings, and can look through. In the scene, someone is actually looking at the heroes, but another someone stabs him/her at the back. On the other side of the painting, the blood is visible, and the two characters noticing it.
– Maybe the last scene, where everyone is standing in a prison (all but the mysterious villain). There is a butler (tall, balding), and I remember also an old lady who was in a wheelchair, and she dies. The buttler put his ears onto the chest of the lady, and after a few seconds, he says she is gone.

Well, this is all I can remember. I had this movie on a video tape, but lost it, and I no clue what was the title. All I know is that my grandparents refered to it as the “crime parody”.