Kate Middleton visited the set of Downton Abbey, ITV's award-winning costume drama, located at London's Ealing Studio. Upon her arrival, she was presented with a posy by four-year-old Zac Barker. She also met his identical twin brother, Oliver. The two child actors both Lady Mary's son, George.

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Kate Middleton receives a bouquet of flowers from Zac Barker, one of the actors who play Master George in Downton Abbey, as she arrives at Ealing Studios to visit the set of of the programmePeter Nicholls/Reuters
Kate Middleton Downton Abbey
Catherine, Duchess of Cambridge is presented with a train for Prince George by Oliver Barker (who plays Master George) during a visit to the set of Downton Abbey at Ealing StudiosChris Jackson/Getty Images

Middleton met stars of the the popular television show including Jim Carter who plays butler Carson and Michelle Dockery who plays Lady Mary Crawley.

The duchess would not be drawn on who her favourite character of the series is when asked by actor Hugh Bonneville, who plays the Earl of Grantham, saying she had to be diplomatic.

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Kate Middleton poses with actress Michelle Dockery (Lady Mary)Chris Jackson/Getty Images
Kate Middleton Downton Abbey
Kate chats to Hugh Bonneville (the Earl of Grantham) and Laura Carmichael (Lady Edith)Chris Jackson/Getty Images
Kate Middleton Downton Abbey
The Duchess of Cambridge chats to actor Jim Carter (Carson) during a visit to the set of Downton AbbeyChris Jackson/Getty Images
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The Duchess of Cambridge meets actress Phyllis Logan (Mrs Hughes)Chris Jackson/Getty Images
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The duchess is shown the Downton Abbey servants' bells by actor Brendan Coyle (John Bates)Chris Jackson/Getty Images
Kate Middleton Downton Abbey
Kate shares a joke with actor Robert James-Collier (who plays Thomas)Chris Jackson/Getty Images
Kate Middleton Downton Abbey
The Duchess of Cambridge poses with cast, crew and producers of Downton Abbey during a visit to the set at Ealing StudiosChris Jackson/Getty Images

The duchess visited hair and makeup departments, toured scenery construction and watched a scene being filmed.

Visiting the kitchen set, where she was greeted by actresses Lesley Nicol and Sophie McShera who play Mrs Patmore the cook and Daisy the kitchen maid, Middleton joked with them about their cooking skills.

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The Duchess of Cambridge chats to actresses Sophie McShera (Daisy) and Lesley Nicol (Mrs Patmore)Chris Jackson/Getty Images
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A cake presented to the Duchess of Cambridge by the Downton Abbey teamChris Jackson/Getty Images
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The Duchess of Cambridge is shown costumes during a visit to the set of Downton AbbeyChris Jackson/Getty Images
Kate Middleton Downton Abbey
Kate watches live filming of a scene during a visit to the set of Downton Abbey at Ealing StudiosChris Jackson/Getty Images
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Kate chats to costume designer Anna RobbinsChris Jackson/Getty Images
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The Duchess of Cambridge chats to Nic Collins as actress Phyllis Logan (Mrs Hughes) is made upChris Jackson/Getty Images

Prince William's wife, who is eight months pregnant, wore an elegant dress from maternity brand Jojo Maman Bebe, which retails for £69. She completed the chic look with black heels and a matching black clutch bag. The duchess is due to give birth to her second child at the end of April.

Downton Abbey chronicles the lives of an aristocratic family and their servants at Highclere House, a Victorian castle used as the location for the drama series. But many of the drama's interior scenes are filmed at Ealing Studios in west London.

The show's writer, Julian Fellowes, described how a 2011 visit to the US by Middleton and her husband came as producers were trying to raise the profile of the show. Fellowes said when the duchess mentioned she was a fan "this went into the media like an Exocet missile. And soon all of America and most of the world knew it".

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Julian Fellowes watches as the Duchess of Cambridge unveils a plaque commemorating her visitChris Jackson/Getty Images

The sixth series of Downton Abbey has been commissioned and is currently in production.