The self-appointed “prince” of Hutt River Province in WA’s Mid West is abdicating due to his declining health at age 91.

The 75sqkm principality, a privately owned wheat property north of Geraldton, claims to have seceded from Australia after a row over wheat quotas in 1970. The tourist attraction has even printed its own postage stamps and currency.

While it has never been recognised by any government and is subject to State and Commonwealth laws, Hutt River Province received an official nod in a letter from Queen Elizabeth II last year on its 46th anniversary.

Leonard Casley, who has reigned for 47 years since the province was founded, says he will abdicate his sovereignty on February 11 and hand it to his youngest son Prince Graeme, whose current titles include Minister of State and Education, and Grand Master of the Order of Wisdom and Learning.

Camera Icon Prince Leonard of Hutt River Province. Credit: Steve Ferrier/The West Australian.

Prince Leonard said being the sovereign for more than half of his life had been rewarding at times and difficult at others, and his health had been going downhill for some time.

“I feel that it is time to hand over at a time when I am still around and thus able to offer help and support to my successor as he settles in to the position,” he said in a statement.

When asked why the reigning monarch had bucked the royal tradition of passing on power to the eldest offspring, Prince Graeme joked he believed he was his father's favourite — just don’t tell the others.

“We have a crown council of three members, so the sovereign puts in a nomination who they believe would be a good candidate,” he told ABC radio.

Play Video Meet the self-proclaimed monarch of Hutt River Province The West Australian Video Meet the self-proclaimed monarch of Hutt River Province

He said his father was suffering shortness of breath from emphysema, but was still energetic most days to welcome visitors and tend his vegetable garden.

The enthronement of Prince Graeme will take place in a chapel named after his mother Princess Shirley, who died in 2013 surrounded by her family, sparking a 12-day period of mourning that ended on her birthday.

The 84-year-old raised seven children, was grandmother to 22 and a great grandmother to more than 30.

Camera Icon Prince Leonard Casley and thelate Princess Shirley. Credit: WA News

Prince Graeme, 60, said he was ready to rule and excited by the prospect of improving relations with the State and Commonwealth.

While the wheat quotas issue prompted his father to consider secession, his mind was made up after the Court government introduced the Kewdale Lands Development Act in 1966 under which any land outside the metropolitan area could be resumed without the governor needing to be notified.

“That was the real catalyst and they've never actually challenged (the secession),” Prince Graeme said.

“We have all these other incidental discussions. I will be trying to bring about a more harmonious relationship with our closest neighbour Australia and the West Australian government."

When The West Australian visited him in December last year, Prince Leonard appeared to struggle to make the short journey up a dusty path from his homestead to his desk at the principality’s government office.

RELATED:Prince Leonard rallies for tax fight

Reaching for the nearest chair, the self-proclaimed monarch needed a rest and took several deep draws from his puffer — the only relief from his debilitating emphysema.

At the time he conceded he “might not make it to next winter”, but vowed to spend his final months as Hutt River’s ruler pursuing the fight against the establishment he began when he seceded.

Prince Leonard’s latest battle, a claim by the Australian Taxation Office lodged in the WA Supreme Court that he owes $2.65 million in unpaid taxes, was a new fight that he believed was a political statement by the Federal Government — one that aims to shut Hutt River down.