Anthony Caro: 'I am playing all day, doing what I love...I want to try it all!'

The first time I visited Anthony Caro's studio was some 20 years ago. I remark to him that his assistant, Patrick Cunningham, is still the same. Caro laughs and says, "Yes, he has been with me for 40 years!"

He has been in this studio the same length of time, moving in when his previous studio, a garage, was flattened to make way for condominiums. The imposing rectangular building, originally a piano factory, is tucked behind a row of terraced houses in Camden. "It was too big for me in those days," he says, but nine years ago his work spilled into two nearby properties, in one of which we are talking.

Lining the walls are the striking abstract canvases of his wife, painter Sheila Girling, whom he married in 1949. He says: "This is the clean area, although when we got it, it was a pipe factory and there was wood dust everywhere. Sheila's studio is upstairs and," he gestures, "I'm over there, and we meet here and have lunch".

Born in 1924, Sir Anthony has been making sculpture since the 1950s. He was knighted in 1987 and received the Order of Merit in 2007. He began as a figurative sculptor before converting to abstraction in 1960, and the then radical step of taking sculpture down from its plinth. He later went further, applying colour to his sculptures' surfaces.

Several trips to America, the first in 1959, helped shape his work, he tells me. "I was never drawn to Paris; I preferred the energy in America," he explains.

He has said that he has been dogged by his connection with Henry Moore, whose assistant he briefly was, and with American sculptor David Smith, who was his contemporary. I tell him I want to set the record straight: I feel that he should be discussed alongside Richard Serra, who I have no doubt was looking at his work in the 1960s and after.

"Philip Glass, the composer, said to me that Serra was aware of my work," he says, then laughs, "but it is not where you get it from but what you do with it." Although he uses a walking stick, Caro is in fine form for a man of his years, leaping up to take me round. He stops first in a nearby room to show me a recent work incorporating coloured Perspex, which he loves for its transparency. He experimented with wood before replacing it with the final, deep red, Perspex.

Beyond piles of rusted steel, squeezing past a fork-lift truck, we enter a world of welding sparks. I ask if he likes making things in different materials. "I want to try it all!" he says. I once told an artist I was jealous that they got to play all day, I tell Caro, and the artist became cross with me. "But that is what it is!" he says. "I am playing all day, doing what I love."