Sandringham; the Royal Family's favourite holiday home. For over 160 years, kings and queens have come to this 274-room retreat to relax in the privacy of the Norfolk countryside. But what really goes on behind the imposing iron gates?

In this series, Nigel Havers reveals the surprising secrets of Sandringham House and its vast 20,000-acre estate. With the help of JJ Chalmers and Raksha Dave we find out what daily life was like for those upstairs and downstairs – and discover why the house had its own time zone for close to a century. We discover the terrifying disaster that almost destroyed the house while Queen Elizabeth II slept inside, and find out just how the royals celebrate Christmas. And we even uncover the story of Sandringham's secret house, where the royals go to hide.

CGI shows how the iconic building has transformed across the centuries as a long line of monarchs added everything from a private bowling alley and home cinema to its very own post office and on-site fire brigade.