Penelope Keith at Her Majesty's Service Episode Rating Graph

Penelope travels around the country to visit the Queen's official residences and meet people with royal appointments. The journey begins in Windsor Castle, where she finds out about Britain's oldest order of chivalry, meets the Royal Herb Strewer and unearths a box of treasure dating back to Elizabeth I. She also takes a trip up the Thames in the gilded barge Gloriana.

Penelope visits the Queen's official Scottish residence, the Palace of Holyroodhouse, and explores the bed chamber once occupied by Mary, Queen of Scots. She also boards the royal yacht Britannia and visits Inveraray Castle, where she meets the Master of the Royal Household of Scotland. At Borthwick Castle in Midlothian, she gets a lesson in archery and talks to the Royal Falconer.

In Northern Ireland, Penelope visits Hillsborough Castle, the Queen's official residence in Northern Ireland. She discovers the daily routine of the household staff during a royal visit, and flicks through a scrapbook of mementos dating back to 1925, which provides an insight into how life in the royal family has changed over the years. She also meets the Queen's bugler, finds an unexpected treasure from the 1953 coronation tour and discovers how in 2012, the Queen played a simple but vital role in uniting two fractured communities in Enniskillen simply by crossing the road.

Penelope concludes her journey with a trip to the Queen's royal residences in Wales and exploring the regal links, including ceremonial investitures, Pembrokeshire corgis and the Royal harpist. She pays a visit to Caernarfon Castle, where Prince Charles was invested as Prince of Wales in 1969, and the Royal Mint, as well as Aberfan in the valleys of south-west Wales, which was the site of a disastrous coal mining accident in 1966. On her travels, she meets champion dog breeders and is serenaded by two male voice choirs. Last in the series.