CAMILLA PARKER BOWLES and KATE MIDDLETON vie for royal assignments.

Her son Prince Charles served in the Royal Navy. Yet when it came time to choose a family member to sponsor the much heralded navy battleship HMS Glasgow, Queen Elizabeth II skipped right over Charles’ spouse Camilla Parker Bowles — and chose her grandson Prince William’s wife, Kate Middleton. “My family’s affection for the Royal Navy is well known,” William, 39, said in an address to officers on June 28. “I know that Catherine will be delighted to join you here in Glasgow for the naming ceremony in due course.”

But there’s one person who is definitely not delighted: Camilla. The naval sponsorship is one of many recent events — including First Lady Jill Biden’s recent visit to the U.K. — which the queen has invited Kate, 39, to participate in rather than the wife of England’s future king. And it’s left Camilla, 73, feeling as though she’s on the losing end of an unspoken competition. “The queen likes Camilla and acknowledges that she’s a huge help in lessening her burden of royal duties,” an

insider shares, “but Kate is undoubtedly her favorite.”

A DIFFICULT PAST

The Duchess of Cambridge has worked hard to win Her Majesty’s favor. “Even though she has a full plate looking after her three young kids, Kate’s the first to volunteer for assignments, before Camilla can even check her schedule. Camilla, quite frankly, finds it annoying,” reveals the insider. “She feels that Kate is a suck-up and rolls her eyes whenever she compliments the queen’s appearance — which is often. Without saying it openly, Camilla feels that

Kate is trying to leapfrog over her to the throne.”

Of course, it isn’t all Kate’s fault. There’s a lot of unpleasant history between the monarch, 95, and Camilla, whose affair with Charles, 72, when he was still married to Princess Diana, was a source of great embarrassment for the palace. Even after more than 30 years, the queen has found it hard to forgive and forget, says the insider, “but Camilla wishes everyone would just move on!” As the insider points out: “At the end of the day, it wasn’t just some fling” between Camilla and Charles, whom the Duchess of Cornwall sees as her

soulmate. Still, the queen “feels that Kate is a better fit to fill her shoes,” notes the insider. “She ticks all the boxes.”

The situation has left Camilla feeling discouraged — but she hasn’t given up the fight. “She’s trying hard to become more relatable,” the insider says of Camilla, who recently set up a book club on Instagram. “She wants the queen and the public to like her. She’s doing everything she can.”

Camilla Parker Bowles is miffed after Queen Elizabeth II picks Kate Middleton over her for a series of royal assignments