British art's grand old man never gives interviews, but here his assistant reveals how he works, and what he thinks of Tracey Emin and Damien Hirst.

Lucian Freud is regularly described as the world's greatest living painter. Now that a new exhibition has just opened in London focusing on his early works, public interest is again high. Yet Freud, as ever, is reluctant to engage with the media.

But one man who will cast light on his working processes is the exhibition's curator, David Dawson, who knows the notoriously interview-shy artist better than most. He has been working as Freud's studio assistant since 1991, and regularly models for him. "I was offered a job with James Kirkland, who was Lucian's dealer at the time," Dawson explains. "I met Lucian and we got on immediately, and it just evolved that I should go and help him. We developed a nice friendship and that is how it all started."

A typical day working with Freud begins at 7.45am. "Every morning, first thing, I run to Lucian and set up the studio. I get the easel out, as well as whatever models are sitting on or lying on, and I put them in the right position. Models come in at 8.30am and then I leave. I am never in the studio when Lucian is painting unless I am sitting myself. It is always a very private space and the studio doors are always closed. So if there is nothing else needed, I can go home and paint [myself]."

He usually returns in the evening to sort things out for the evening sitting or sometimes to act as model himself.

At 85, Freud is working as hard as he has ever done, says Dawson. "He paints every day. There are four paintings on the go at the moment. He has day and night studios. In the day studio he paints in daylight, and at night he paints in electric light. For an 85-year- old he is amazing, and the quality of his work is not diminishing at all."

So what is it like to sit for him? There are six paintings featuring Dawson and a seventh is currently in progress. "It is a unique experience," he says. "Each painting takes about a year and sittings are always one on one. It is very concentrated and at times very relaxed just being in each other's company. Lucian is a great conversationalist, but you learn to spot the pauses when he is concentrating and you just naturally don't talk."

The first painting Freud made of Dawson shows him lying naked on a bed with Freud's pet whippet Pluto, with another pair of legs sticking out from under the bed. Dawson modelled for those as well. "I was stuck under the bed for six months," he laughs. "It was a long, tall painting and there was a huge area at the bottom. Lucian wanted excitement and he tried many things: a big plant that had fallen over, a pair of trousers, and then he said: ‘Just go under the bed and have your legs pointing out.'" The painting is now in the Art Institute of Chicago.

Freud was born in Berlin but came to Britain in 1933 at the age of 10. He avoided much of the trauma suffered by many refugees from the Nazis, says Dawson. "Unlike his friend and fellow painter Frank Auerbach, who came alone from Germany, Lucian had a secure sense of family around him, his brothers, both parents and his grandfather," he says. "This show is all about the war ending and Europe being open again. He went to France as soon as he could [after the war] and met Picasso and other artists there. The paintings are all about how free life was again."

Freud is, of course, the grandson of Sigmund Freud. What sort of relationship did they have? "He was very fond of his grandfather and has great admiration for him," Dawson reveals. "Recently the publishers Taschen brought out a monograph about Lucian and he insisted on having ‘Lucian Freud' on the cover rather than just ‘Freud' because to him ‘Freud' means his grandfather."

Like his grandfather, Freud is not a practising Jew but is interested in discussing religion. "A Jewish art collector is flying in from New York once a month for sittings at the moment. Lucian is interested in talking to him about his beliefs. But being Jewish isn't a big part of Lucian's life, though he would never be against it. He just got caught up in painting. That is his obsession."

Dawson reveals that Frank Auerbach is very important to Freud. "They really are the closest of friends and have been for an awful long time. Every time a painting is just about finished, Frank always comes round to have a look and Lucian listens to Frank's view."

Freud is also interested in the work of the younger generation of artists and visited Sotheby's in London recently to preview the works of Damien Hirst before they were auctioned. "Lucian very much wants to see what else is going on in the art world. He is very fond of Damien and they go out for supper sometimes. Damien is clear about what he is doing and Lucian likes that clarity." Through Dawson, Freud has also met Tracey Emin. "I was at college with Tracey and shared a studio with her. Lucian likes her and thinks she has very nice manners."

While preparing for the exhibition, Freud asked Dawson and archivist and curator Catherine Lampert to trace a portrait of the millionaire antique book-dealer Bernard Breslauer, who had died in 2004. As reported in the JC earlier this year, they discovered that Breslauer had not liked the way he was painted with a double chin and had destroyed the work. Freud was reported to be "disappointed and frustrated". However, Dawson says that, in most circumstances, Freud is able to separate himself from his work. "When paintings leave the studio, he lets them go. They are out in the world and he is concentrating on what is in front of him."

He is, however, rigorous about ensuring the quality of the work he leaves for posterity. "Lucian has always edited his work very strongly so he has never let anything out of the studio that he is not happy with. There isn't any really poor quality work out there. We destroy anything else."

Early works by Lucian Freud are at Hazlitt Holland-Hibbert, 38 Bury Street, London SW1 (www.hh-h.com) until December 12