Next week Kate will meet screenwriter Julian Fellowes, as well as cast members Dame Maggie Smith, Hugh Bonneville and Robert James-Collier, who play Lord Grantham, Thomas Barrow and the formidable Dowager Countess respectively.
Although Highclere Castle in Hampshire is used for exterior shots of Downton Abbey and most of the interior filming, the kitchen, servants' quarters and working areas are constructed sets at Ealing Studios.
During her visit on 12 March the Duchess, who is expecting her second child, will watch one take of a scene being filmed for the sixth series, which will air on ITV later this year.
Kate, who will be escorted around the set by series executive producer Liz Trubridge, will also pose with cast members and crew for photographs and witness make-up artists, costume designers, seamstresses and cutters at work.
Finally, the Duchess will unveil a plaque alongside Bonneville to commemorate her visit.
Ealing Studios have been used to fill the likes of Birds of Prey, Notting Hill and The Royle Family since 1902.
This week Sophie, Countess of Wessex and Mexican First Lady Angelica Rivera visited the set, where they posed for a photograph with Bonneville, as well as his on-screen wife Elizabeth McGovern and the TV couple's daughters Michelle Dockery and Laura Carmichael. Sophie MsShera, who plays cook Daisy, who also present.
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