I must have been six or seven when I first saw Buster Keaton. We were living in New York, and my father took me to the Museum of Modern Art in New York, where I saw some Keaton and some Chaplin pictures. I was just a kid, but I loved him right away, and that was the start of the great affection I have for silent comedy.

Somebody once said to Chaplin: “Your camerawork is not very interesting,” and he replied: “It doesn’t have to be. I’m interesting.” But Keaton was great with the camera, and great with the acting as well. While directing the documentary The Great Buster: A Celebration, I came to care for him even more because he is so precise and the timing of the jokes is just flawless.

I don’t have a favourite Keaton movie. I think Steamboat Bill, Jr (1928) is probably the funniest, just in terms of laughs. The gag in that film when the house falls on him, and he ends up in the window … oh my God, to have the balls to do it at all, just to take that chance, is amazing.

Sherlock, Jr (1924) is the most brilliant, and Our Hospitality (1923) is an underrated masterpiece: the stunt in which he swings on a rope into a waterfall is just mind-boggling. The General (1927) is probably the best-directed one – it’s very daring in terms of getting laughs about people getting killed.

Keaton didn’t make a bad feature. I think the weakest one is Seven Chances (1925), but even that has some great stuff in, such as the chase with the women at the end.

Sound in pictures didn’t arrive until my father was 30, so he grew up with silent film, and I came to feel that the centre of the art of cinema was silent pictures: telling stories visually. That’s the key, I think, to making a good picture. One of the best films that came out last year in that sense was Knives Out – very visual and very funny.

The main influence of Keaton on my work was in What’s Up, Doc? We had a chase sequence that went on for 12 minutes and I kept saying: “This is my Buster Keaton chase.” That was probably a bit presumptuous of me – I don’t think it’s as good as Keaton, but I was thinking of him when I filmed it. Keaton said: “You have to always see a comedy actor’s feet and legs,” meaning you have to see the full figure when he’s in action. I kept that in mind when Ryan O’Neal was running alongside Barbra Streisand on the grocery cart.

There was a joke in the sequence that Cybill Shepherd came up with, which is the one where the garbage cans start chasing a guy on the street, and he jumps over the fence. That was based on Cybill’s joke, which she stole from Keaton. It all goes back to Buster.

The silent era has, sadly, been forgotten by younger people. They think of it like Sanskrit or something. I put as many clips into the documentary as possible because there’s no other way to explain the extraordinary physicality of Keaton and his perfect timing. You can talk about it, but you can’t really feel it unless you see it. I tried to include members of the audience who didn’t know anything about him to begin with, and the people who have seen it tell me that it made them want to see more Keaton. Which was the intention!

His films are the most modern of the silent comedies because Harold Lloyd’s essential character, the college square, has pretty much disappeared, and Chaplin was always idiosyncratic and kind of Victorian. You look at any of the features Keaton made, though, and they seem as if they were conceived in the present time.

Keaton used to say that he was too busy working to smile. But you can see plenty of nuanced expressions on his face. Orson Welles loved him, and we talked about Keaton quite often. He would always say: “Look at that beautiful face.”

It’s a regret of mine that I never met Keaton. In around 1965, I started trying to track him down and it turned out he was living just a few blocks from where we were living. But then he died suddenly. I would have liked to tell him I thought he was a genius.

In 1928, Keaton signed with Metro-Goldwyn-Mayer (MGM) and he always said that this was a big mistake: the change in his work was immediate. You can see it in The Cameraman (1928), which is the best of the MGM pictures, but it’s not nearly as good as the earlier features. There’s a long baseball sequence in there with Keaton running around the bases, and it’s unbearably boring. He never would have left that in the picture if he had had the control. Later, he appeared in a supporting role in In the Good Old Summertime (1949) – which is a remake of Ernst Lubitsch’s The Shop Around the Corner (1940) – and it’s pretty poor; nothing like Lubitsch. It’s depressing to see Keaton in such a small part. They didn’t know what to do with him. He’s the only one who knew what to do with himself.

I guess I am quite protective of his memory, which is why in my narration I wait to discuss his great features until the end of the documentary, rather than end on his sad decline and the alcoholism. Some people weren’t sure about that, but I think it makes the picture work. There’s an old showbiz adage: “Always leave ’em laughing.”

The Great Buster: A Celebration is released in the UK on 20 March with a Q&A screening with Paul Merton at Picturehouse Central in London on 11 March