Is it the scriptwriting?

John Cleese and Connie Booth would not write a single word of dialogue until each plot was meticulously worked out. "Some people try to write comedy by starting at scene one and writing the dialogue," Cleese explained in "Fawlty Towers -- Fully Booked." "The chances of them getting to a satisfactory ending are one in a hundred. You've got to know where you're going while you're building the thing."

While script length for sitcoms at the time averaged 65 pages, each script for one episode of Fawlty Towers often came in at 140 pages or more.

Was it the intensity, non-stop antics and overall physicality?

"I've always had a tremendous love for farce because what I like to do more than anything else is to really laugh," Cleese said. "What I love is the intensity and the emotion because with that comes more frantic behavior, more energy and the possibility of huge laughs. What a lot of people haven't spotted is that Fawlty Towers is just  little 30-minute farces that start very, very low key and finish up absolutely frantic."

Or was it Cleese's demand for perfection in the production?

There were more than 400 camera angles and cuts in each half hour of Fawlty Towers.  He expected each cast member to have completely memorized his or her lines by the time weekly rehearsal began Wednesdsay morning. Daily rehearsals were rigorous, including the two on Sunday afternoon just hours before taping began at 8:30 p.m.

"The sheer speed in which we rehearsed was incredible. We could laugh an awful lot, but we worked very, very hard at it to get it right," Cleese recalled.