Vogue cover star Kate views photographs of herself at National Portrait Gallery

The Duchess of Cambridge has viewed photographs of herself striking a pose in the National Portrait Gallery.

Kate, a Vogue cover star who adorns the front of the fashion bible's June centenary issue, looked chic in Alexander McQueen for her third engagement of the day.

She is shown looking casual and relaxed in the pictures, taken in the Norfolk countryside earlier this year, in a marked departure from more formal official images of the Royal Family.

The Duchess of Cambridge arrives at the National Portrait Gallery

The Duchess of Cambridge arrives at the National Portrait Gallery

In a black-and-white close-up shot, the Duchess is wearing a black fedora hat from Beyond Retro and a charcoal brown double-breasted suede coat and white shirt, both from Burberry.

In another, a colour photo shot in soft January sunlight, Kate is leaning on a rustic gate, wearing a black and red striped long-sleeved top from Petit Bateau and black Burberry trousers.

The photos, taken by British photographer Josh Olins, are part of the Vogue 100: A Century Of Style exhibition, and are on public view in the National Portrait Gallery, where Kate has been a patron since 2012.

The latest photos of the Duchess were styled by British Vogue fashion director Lucinda Chambers and a colour image of the Duchess in the brown Burberry coat and fedora is on the cover of the magazine's June issue, which is out on Thursday.

Chatting to Olins, Kate said of the portraits: "It doesn't look like January. You did a very good job."

The Duchess, a keen photographer herself who has taken official pictures of Prince George and Princess Charlotte, discussed photography with Olins as well as the exhibition decision-making process.

She told Olins: "Thank you Josh. Really good to see you again."

As she was shown around the exhibition, Kate asked lots of questions and commented on the glamorous images.

She said one had "fantastic texture" and also remarked on the decision to frame a collection of images with red frames on a red wall - a look she described as "red on red".

Kate asked about how the exhibition was "split up into different sections" as each room shows off a different decade.

Nicholas Cullinan, director of the National Portrait Gallery, showed the Duchess around the exhibition, and afterwards said: "She has a good eye."

Talking about Kate's reaction to seeing the portraits of herself hanging in the gallery, he said: "I think she was very pleased by them."

Mr Cullinan praised Olins and said he captured "something very fresh and very spontaneous and relaxed".

Asked what Kate was talking about as they browsed the exhibition, the gallery boss said: "She's really knowledgeable. I mean this is not the first time I've met her, and what came across in my first meeting with her is that, obviously she studied art history and she has a real understanding of art history and especially photography, but also a real enthusiasm for it.

"She really is genuinely engaged and she was asking some very intelligent and engaged questions tonight as we went around.

"It's always a joy to talk to someone when they really understand and have a love for a subject."

He said she asked "detailed" questions about the process, the technicalities, from taking an image to choosing how to print it and how to hang it.

Mr Cullinan added: "She definitely knows her stuff."

Kate wore her trademark nude heels and had her hair loose at the gallery, where she was greeted by editor-in-chief of British Vogue Alexandra Shulman.

The Duchess earlier revealed that her family is enjoying the pitter-patter of tiny feet - after they took in a pet hamster.

As she opened a new children's play area at Hampton Court Palace, she told a schoolgirl that a regal rodent called Marvin had joined the Royal Household.

The Duchess was talking to some children when she made the revelation to Darcey from St John the Baptist School in Hampton Wick, Surrey.

The nine-year-old said of her conversation with the royal visitor: "She said she has a hamster, and (Princess) Charlotte really likes it because the whiskers always tickle her face."

Marvin joins Lupo the dog in the Cambridge family's roster of known pets.

The Duchess was at the former royal palace, once the home of Henry VIII, to unveil its Magic Garden.

Wearing a summery grey-blue silk dress by Roksanda under a jacket by Michael Kors, the free-spirited Duchess told how she was desperate to "take off her shoes and run around" the play area in the palace tiltyard as she was shown some of its unique design features.

The Duchess of Cambridge arrives at the National Portrait Gallery

The Duchess of Cambridge arrives at the National Portrait Gallery

The Duchess of Cambridge meets children at Hampton Court's recently unveiled Magic Garden play area

The Duchess of Cambridge meets children at Hampton Court's recently unveiled Magic Garden play area

The area was designed by RHS Chelsea award-winning landscape architect Robert Myers

The area was designed by RHS Chelsea award-winning landscape architect Robert Myers

The play area draws inspiration from the myths and legends of the Tudor court

The play area draws inspiration from the myths and legends of the Tudor court

Kate officially opened the play area

Kate officially opened the play area

Kate waves to families in the play area

Kate waves to families in the play area

The Duchess of Cambridge meets children at Hampton Court Palace

The Duchess of Cambridge meets children at Hampton Court Palace

Kate stares into the mouth of a dragon (AP)

Kate stares into the mouth of a dragon (AP)

The Duchess was taken on a tour of the area

The Duchess was taken on a tour of the area

Kate looked the part in a Michael Kors coat dress, previously worn on her 2014 tour of Australia

Kate looked the part in a Michael Kors coat dress, previously worn on her 2014 tour of Australia

Kate's hair was styled in loose curls (AP)

Kate's hair was styled in loose curls (AP)

Kate took the time to stop and chat to schoolchildren

Kate took the time to stop and chat to schoolchildren

The Duchess did not bring her own children to the park

The Duchess did not bring her own children to the park

Children play as the Duchess of Cambridge views Hampton Court's recently unveiled Magic Garden

Children play as the Duchess of Cambridge views Hampton Court's recently unveiled Magic Garden

The Duchess views a cake decorated with dragons and magical creatures

The Duchess views a cake decorated with dragons and magical creatures

Kate later attended a lunch at Spencer House in support of the Anna Freud Centre

Kate later attended a lunch at Spencer House in support of the Anna Freud Centre

She had changed out of the coat-dress and into a silver day-dress

She had changed out of the coat-dress and into a silver day-dress

The Duchess of Cambridge at a lunch in support of the Anna Freud Centre at Spencer House, London

The Duchess of Cambridge at a lunch in support of the Anna Freud Centre at Spencer House, London

Kate mingles with guests at Spencer House

Kate mingles with guests at Spencer House

The Duchess of Cambridge attends the UK's Creative Industries Reception as part of the Government's GREAT campaign at the Royal Academy of Arts

The Duchess of Cambridge attends the UK's Creative Industries Reception as part of the Government's GREAT campaign at the Royal Academy of Arts