Seven decades of Lucian Freud's paintings, including his famously fleshy and unforgiving nudes, are on show at Britain's National Portrait Gallery.

Reporters got a sneak peek at the extensive retrospective in London on Wednesday.

The renowned British artist had been working on the exhibition before his death in July at the age of 88. His final, unfinished work — Portrait of the Hound 2011 — is included among the more than 100 paintings featured.

Over the years, even when realism and portraiture became less fashionable in the art world, Freud continued painting his raw, unrelenting, honest depictions of the human form.

"They sometimes feel in your face and very explicitly naked," National Portrait Gallery director Sandy Nairne said of Freud's work.

"But that was always with the co-operation of the sitter. In the end, they were sympathetic.…None of these are casual sitters. They are not figures — they are individuals."

Freud's subjects ranged from famous figures such as supermodel Kate Moss and performance artist Leigh Bowery to regular members of the public such as employment agency staffer Sue Tilley, who posed for Freud on several occasions during the 1990s.

Measuring one metre high by two metres wide, Freud's substantial portrait of Tilley entitled Benefits Supervisor Sleeping sold for $33.6 million US in 2008, setting a record for auction of an artwork by a living artist.

"He was a marvel, really, a complete one-off. He's a person you'll never meet again," Tilley told reporters on Wednesday.

She described the artist as "exciting, interesting, funny and serious — every single personality trait wrapped up in one person."

Royal preview

Catherine, Duchess of Cambridge, who studied art history, will receive a royal preview of the exhibit on Wednesday before its official opening to the public on Thursday. (Ian Gavan/Getty Images)

Catherine, Duchess of Cambridge, will attend a royal preview of Lucian Freud: Portraits before it opens to the public on Thursday. Having studied art history and as a new patron of the gallery, Kate will likely be familiar with Freud's work, according to curator Sarah Howgate.

"I'm sure she's already familiar with Lucian's work but she won't have seen this body of work before. I think she'll thoroughly enjoy it," Howgate said in an interview.

Tilley added that she didn't feel any discomfort about anyone — the duchess included — examining the show's four large nude canvases that Freud painted of her.

"I'm not embarrassed about her seeing me naked — I'm a human being. I may not be the most gorgeous one under the sun but that's what I am," Tilley said. "It's art, you know. Poor woman, I'm sure she's seen things before."

Lucian Freud: Portraits continues in London through May 27 before moving to Modern Art Museum of Fort Worth, Texas, from July 1 to Oct. 29.

"We have nothing like this in America.… We are the land of Photoshop. We are the land of sleek models. We are the land of no wrinkles," said Michael Auping, chief curator of the Texas museum.

"It disturbed our sense of abstraction and minimalism. [But] over the years we came to embrace Freud."

With files from The Associated Press