Prince Harry already heading back to US after coronation

Prince Harry’s return to the UK was short-lived.

A source told The Post that Harry, 38, left the church Saturday after the coronation service for his father King Charles III, 74, and is en route to Heathrow Airport.

The Duke of Sussex will make it home to California in time for son Archie’s 4th birthday party, the source added.

Harry — who looked sad and lonely at the ceremony — spent less than 24 hours in the UK, arriving on a commercial flight Friday evening.

He spent the night at Frogmore Cottage, despite being kicked out earlier this year by Charles so the home could go to his own brother, Prince Andrew.

The duke arrived to King Charles’ coronation at Westminster Abbey solo, sans wife Meghan Markle, 41. This was the first time he has seen his father since he released his bombshell memoir, “Spare,” in January.

Harry arrived with his cousins, Princess Beatrice and Princess Eugenie. He seemed to get snubbed several times during the ceremony.

He was seated in the third row beside Eugenie’s husband, Jack Brooksbank, and Princess Alexandra.

First-row seats are reserved for full-time working royals, including his estranged brother, Prince William, 40, and wife Kate Middleton, 41.

Harry was seen smiling as he took his seat, though he was blocked by a giant feather atop Princess Anne’s hat.

After much speculation, Buckingham Palace announced in April that Prince Harry would attend his father’s coronation ceremony without Markle and their two children.

“Buckingham Palace is pleased to confirm that the Duke of Sussex will attend the coronation service at Westminster Abbey on May 6,” a spokesperson confirmed. “The Duchess of Sussex will remain in California with Prince Archie and Princess Lilibet.”