Bob Newhart, the veteran US standoff who is winning a new generation of fans through guest appearances on the hit TV comedy The Big Bang Theory is, above, all, a gentleman. I know this for a fact.

I wrote a column at the start of the year in which I mentioned the great man's talents as a supreme monologue artist. Thanks to the power of, it came to the attention of Bob - he won't mind me calling him that - in Los Angeles.

Within hours, his PA had sent me an email telling me that Bob had read the piece, and had enjoyed it. Within days, she had scanned and sent me a hand-written note from him which said: "Dear Drew, because of a service I have I was able to read your article in which you mention my work very favourably.

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"Thank you. It is great to be remembered, However, I do have to correct a couple of things. I still do about 20 stand-up dates a year here ... and still enjoy doing it, as you mention, at 84.

"Sincerely, Bob Newhart.

"PS. Oh, and a recurring role on The Big Bang Theory."

Oops. I'd made the mistake of saying that Bob was "largely retired". Considering that only a month previously he'd received an Emmy award - his first win, after six nominations, the first of which was in 1962 - for his guest appearance as Professor Proton in The Big Bang Theory, that was a silly error.

Bob, though, was gracious, and agreed to an interview covering his life and work. It was great to hear his voice again; I was familiar with it from his classic album, the Button Down Mind of Bob Newhart, which was recorded in 1960.

For those unfamiliar with that voice, it is characterised by a slight stammer; I asked him if that had ever been a hindrance. "No," he said, "It's the way I talk and comedically a stammer has always been helpful."

By way of illustration, he related this anecdote: "There was a famous comedian named Joe Frisco. No-one knew if he only stuttered on stage.

"One story attributed to him: he was staying at a flop house. He was going through some bad times and he ran into a friend of his who had no place to stay.

"So Joe said: 'Well, you can s-s-stay with me but you have to come in through the fire escape because if the clerk knows I've got someone staying with me in the room he's going to charge me double'.

"The bank clerk eventually realised and phoned up and said: 'I'm going to charge you double'. So Joe said: 'Oh-oh-ok ... but s-s-s-send up another Gideon Bible!

"So that gives you an idea of the place of the stammer in comedy..."

Bob's stammer certainly helps in the timing of some of his greatest routines, which involve him holding down one end of a conversation, subtly allowing the imaginary second party to provide the comedy.

One of his most famous is The Driving Instructor, where he invites his audience to imagine that he is the titular instructor seated in a car; next to him is a pupil, Mrs Webb, he is meeting for the first time: "How fast were you going when Mr Adams [her previous tutor] jumped from the car? 75. And where was that? In your driveway. How far had Mr Adams gotten in the lesson? Backing out. I see, you were backing out at 75 and that's when he jumped..."

It's a routine he has performed flawlessly for more than 50 years. Except for one occasion - during the Royal Variety Performance of 1964. "I was doing a show in New York and flew in for the performance at the weekend. I remember I did the Driving Instructor and seated, as I always was, I looked to my left and began talking to Mrs Webb. Then I stopped and realised that I was in England, and Mrs Webb would be on my right..."

It would still have got a laugh, I have no doubt. After all, whatever he does, he's comfortable in the driving seat.

Read my full interview with Bob Newhart here.