Henrietta Russell, Dowager Duchess of Bedford became a New Zealand citizen late last month, The New Zealand Herald reported.
The duchess, whose husband Robin Ian Russell was the 14th Duke of Bedford, swore her oath of allegiance and sang the New Zealand national anthem at a small ceremony at Matamata Town Hall.
"I am absolutely thrilled to become a New Zealander", she told the Herald.
"I fell in love with New Zealand when I was 11. I was 51 when I eventually arrived here.
"Geography was my passion at school and that was rivers and mountains, not city planning like it is now."
The duchess said the ceremony was "lovely".
"What was wonderful was I am English, and the monarchy has always existed for us, but I didn’t realise I was going to have to pay allegiance to King Charles. I have never had to pay allegiance and that was such a lovely feeling as well and made me feel unity."
Her husband and children are direct descendants of former United Kingdom prime minister Lord John Russell, also secretary of state for the colonies in 1855, when New Zealand was a British colony.
"I feel very proud, very grateful and very happy to become a New Zealand citizen because I’m a little old, but have always been a citizen of New Zealand at heart", she said.
The 84-year-old, who has several properties in the UK and in New Zealand, including homes in Arrowtown, Tekapo, Matamata and Te Aroha, arrived in New Zealand in 1991 and bought a farm three years later.
She is also prominent in the New Zealand horse breeding industry and has thoroughbreds in both hemispheres — including Snap, a champion filly.
Her husband’s Woburn Estate in the UK has been in the Russell family for more than 400 years, and has a safari park, three international golf course and its own abbey.
The vast estate is open to the public to visit.
She has three sons: Andrew Ian Henry Russell (62), the 15th Duke of Bedford, Lord Robin Loel Hastings Russell, 61, and Lord James Edward Herbrand Russell, 49.
"My husband died 20 years ago and by then Andrew was running the estate, and that’s when I decided I was going to spend more time here", the duchess said.
She said New Zealand was the "most straightforward normal country" she had been to, and was why she decided to become a citizen.
— Staff reporter