LONDON -- In a first, Queen Elizabeth II will remain in Scotland, where she is taking her summer break, to receive Britain's outgoing Prime Minster Boris Johnson and his successor next week, royal officials said Wednesday.

The 96-year-old monarch traditionally holds audiences with outgoing and incoming prime ministers at Buckingham Palace, her official London residence. This will be the first time in her 70-year reign the monarch appoints a new prime minister away from Buckingham Palace.

Officials said Johnson will travel to Balmoral Castle, the queen's summer holiday home in the Scottish Highlands, to formally tender his resignation on Tuesday. His replacement -- either Foreign Secretary Liz Truss or former Treasury chief Rishi Sunak, the two finalists in the Conservative Party leadership race -- will also make the trip on the same day.

The queen has been served by 14 prime ministers during her reign. Formally appointing the premier is part of her duties as head of state.

The queen, who celebrated her Platinum Jubilee this year, has been having mobility problems and has cancelled some engagements in recent months. She now regularly uses a walking stick.

British media reported that the decision to have her remain in Scotland was made to provide certainty for the political handover arrangements.

The monarch moved to Windsor Castle, west of London, at the beginning of the coronavirus pandemic and now spends most of her time there.

Johnson announced his resignation in early July. His Conservative Party is set to announce his successor on Monday.