In 1963, he was appointed to the post of Constable of Caernarfon Castle and when the young Prince Charles became Prince of Wales, he was largely responsible for organising the investiture ceremony in the castle. Princess Margaret regularly spent weekends at Plas Dinas during this period in their marriage and was highly regarded by the locals. In fact they still recall their memories of Her Royal Highness today.
Plas Dinas still retains many family portraits, memorabilia and original furniture. It presents the opportunity to enjoy the ambience of a genuine Welsh gentleman's country residence, largely unspoilt by its conversion into luxury accommodation, telling the story of the much loved Armstrong-Jones family.