King Charles crowned in once-in-a-generation ceremony

The once-in-a-generation spectacle of a British coronation kicked off Saturday for the crowning of King Charles III — but the historic occasion was marred by family drama.

Amid the excitement pomp and ceremony, the Westminster Abbey service marked the first time that rogue royal Prince Harry, 38, came face-to-face with his dad, 74, since the release of his protocol-shattering memoir, “Spare.”

It’s also the first time Harry will see his estranged brother Prince William and his wife, Kate Middleton, 41, and their kids — Prince Louis, 5, Princess Charlotte, 8, and Prince George, 9.

But while the Prince of Wales and his family had the front-row seats reserved for full-time working royals, Harry was demoted to the third row with Jack Brooksbank, the husband of his cousin Princess Eugenie, and Princess Alexandra, a cousin of his late grandmother Queen Elizabeth II.

Scandal-scarred Prince Andrew, 63, also in attendance, was booed as he traveled through London to attend the service.

As non-working royals, neither Harry nor Andrew will play any role in the coronation service — and neither will take part in the joyous procession back to the palace.

But while Andrew was permitted to wear his formal garter robes to the ceremony, the Duke of Sussex, accompanying Andrew’s daughters Princess Beatrice and Princess Eugenie, arrived at the Abbey in civilian dress — not his cherished military uniform.

His morning suit was spiffed up with a line of medals.

He walked up the aisle to his seat alone, as wife Meghan Markle, 41, remained thousands of miles away in California with their kids, Archie — who turns 4 Saturday — and Lilibet Diana, 1.

Spectators criticized the new king’s willingness to include his straying son in his momentous day.

“Harry should not be here. He’s been very disloyal to the royal family,” Jaquie Cullen of Liverpool told The Post.

“I was a big fan of Harry before Meghan came around. He was a good, cheeky kid,” agreed Bernie Cullen, Jaquie’s husband. “I think Meghan is very controlling.”

Mal Hill of Manchester said she was “not too happy about Harry attending.”

“I think he’s not stuck to the code,” she sniffed. “If he had something to say he should’ve said it to the family.”

But they were more forgiving of the presence of Prince Andrew, the king’s disgraced brother.

“Harry scarred the British spirit more than Andrew,” Jaquie Cullen argued. “Because against Andrew are only allegations but Harry has done the unforgivable.”

The coronation festivities began at 10:20 am local time as a military band played “God Save the King” for Charles and his wife, Queen Camilla, as they left Buckingham Palace in the Diamond Jubilee State Coach, both arrayed in formal white Robes of State.

Moments earlier, the Royal Family’s website ditched the “Queen Consort” title that it had previously used for Camilla – referring to her for the first time as “The Queen.”

“Her Majesty The Queen (formerly HRH The Duchess of Cornwall) supports her husband, formerly The Prince of Wales, now His Majesty The King, in carrying out his work and duties,” the website now reads.

Thousands of spectators lined the streets of London under gray, misty skies and cheered for their new king, who formally takes the throne eight months after the 70-year reign of his mother Queen Elizabeth II ended with her death in September.

Charles is the 40th monarch to be crowned in Westminster Abbey since it was established in the 11th century as the home of the nation’s most solemn ceremonies.

Prince George, now second in line to the throne, serving his grandfather as a page, followed Charles into the church as a choir sang a greeting.

In the ancient ceremony, expected to last two hours, the Archbishop of Canterbury will anoint Charles as the head of the Church of England — and, at last, place St. Edward’s Crown upon his head to proclaim him as Britain’s new monarch.