The comment was sparked due to concerns over who would act as “regent” to Prince George should anything happen to Prince William. When the reigning monarch is unable to discharge their duties, due to age or ill health, a regent is appointed to undertake many of these functions for them.
The Duke and Duchess of Sussex are currently living in California having stepped down as senior members of the Royal Family last year.
On Monday it was announced the couple will record a 90-minute interview with talk show host Oprah Winfrey, sparking concern in royal circles.
Robert Jobson, royal correspondent for Australia’s Sunrise, said on Twitter: “The issue is with a very elderly monarch, and Charles in his 70s, if anything happens to William, who will be “acting monarch until George comes of age?
“I don’t think the public would accept part-time Harry or great uncle Andrew as it stands.”
Andrew has been embroiled in controversy over the past couple of years over his relationship with convicted American sex offender Jeffrey Epstein.
Prince Harry is currently sixth in line to the British throne, following his father, brother and brother’s three children.
Mr Jobson asked: “If anything happens to Charles and William would Harry or Andrew be asked to be regent to a young George?
“Surely only those who are working royals should be in the line of succession.
“[Princess] Anne should be higher up the chain.”
Harry and Meghan’s interview with Oprah is due to be broadcast in March.
It is expected to be the first time the couple have discussed in detail their decision to step back from frontline royal duties last year.
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7:50am update: Queen has every faith in Prince Harry in 90-min ‘nothing off limits’ tell-all interview
The Queen has every faith Prince Harry and Meghan will honour royal protocol in their “intimate” Oprah Winfrey TV interview.
The Duchess of Sussex will stand by a promise to uphold Her Majesty’s values when they appear in the 90-minute prime time show – although a friend of the billionaire host said: “Nothing is off limits”.
Veteran royal watcher Joe Little, managing editor of Majesty magazine, said: “The Queen will put faith in the loyalty of her grandson and the fact that he will always be a member of the Royal Family and, she will hope, won’t want to damage the monarchy.”
He added: “This isn’t going to be an unscripted interview. It’s going to be carefully thought out and choreographed. But looking at the history of royal interviews, you just wonder if this will trip them.”