Heir we go, Harry! Will the Duke of Sussex still be king of the misery memoir?

He may have slipped to fifth in line to the throne, but at least the Duke of Sussex has the consolation of being the king of misery memoirs. But could even that title be wrested from him?

I ask this because of the expected publication of a new, compelling work by a man who suffered the loss of both his sons.

Thrice-married Nicholas Monson, whose eldest son was killed at the hands of Kenyan police, says his book also details an old-fashioned childhood, including the first time he was beaten.

“It was at my nursery school, Falkner House in Notting Hill,” Lord Monson, 68, tells me.

“I was five or six,” he recalled, adding that the school principal, who was smiling, told him to take off his shorts and pants — and then hit him with a hairbrush.

At least the Duke of Sussex has the consolation of being the king of misery.

“The shock was so great that I peed on his lap,” says Monson, who playfully suggested to a friend that he call his book “Heir.”

The friend, Francis O’Toole, then arranged a photo shoot with Hollywood photographer Rory Lewis. Monson approves of this tongue-in-cheek photo and assures me that his memoir will strike a very different tone than Prince Harry’s.

“He complains about being a ‘spare,’ but then again, that’s everyone who’s not an eldest son,” Monson said, adding that while his childhood wasn’t pleasant, his adult life has been “wonderful” — even if it’s been peppered with tragedy.