Kate Middleton given stark warning by Camilla to stop marriage to William breaking down

Kate Middleton is believed to have been given a vital warning about how to act within her marriage to Prince William in order to keep their royal matrimony thriving. 

• Kate Middleton's marriage to Prince William is said to have been preempted by some important advice from Duchess Camilla. 
• The Duchess of Cornwall offered the wise insight as a woman who has been in a relationship with future King, Prince Charles, for decades. 
• This royal news comes after Camilla's nickname from Kate's kids was revealed—and she's not called granny. 

According to a royal expert, Camilla decided to impart some much-needed knowledge to Kate when she was in the early years of her romance with Prince William. 

The Duchess of Cornwall, who lives at London's Clarence House with Prince Charles, reportedly made sure Catherine was clued up on everything she needed to know on how to make sure her marriage to a King-to-be stood the test of time.

According to author Robert Lacey, Camilla's essential tip for Kate was to make sure her life moulded to the way William leads his, in order to make the union last. 

In his royal biography about Prince Harry and William's ongoing feud, Robert penned, "Camilla had confided to Kate the secret of hanging on to a busy prince: fit your timetable - well, basically your whole life - around his."

Having such a rare experience in common, the two will-be Queen Consorts understandably have built a close bond, often being photographed laughing together, in warm conversation, when the two of them step out for royal duties together. 

Most recently, Kate and Camilla were joined by Prince Charles in London as the three of them went to work together, without William, for a day with The Prince's Trust. 

As images taken on the royal day out (which saw Kate re-wear one of her favorite winter outfits) flooded the internet, royal fans were quick to share their joy over seeing Kate and Camilla together again. 

"Love this bond. 😍😍," one fan wrote on Instagram. 

"I love how they work together. One can see how much Catherine enjoys being with her in-laws," a second agreed, while a third chipped in to say, "I loved this joint family engagement!"