Watch this video and more on True Royalty TV
On the final leg of her journey around Royal Britain, Penelope Keith visits the stunning Caernarfon Castle in Wales which astonishingly dates back to 1088. She also meets some rather special dogs!
In Northern Ireland, Penelope Keith uncovers an unexpected treasure dating back to the Coronation at the magnificent Hillsborough Castle.
Presented by Penelope Keith, At Her Majesty's Service takes a fascinating look behind the scenes of the Queen's official Royal residences beginning with Her Majesty's beloved Windsor Castle.