Camilla Parker-Bowles is allegedly upset that Kate Middleton cancelled her very first solo trip to Malta due to hyperemesis gravidarum – acute morning sickness.

Last week, Clarence House confirmed the Duchess of Cambridge is pregnant.

The 32-year-old royal was asked by her doctors not to make the trip as she is still very ill with hyperemesis gravidarum, a potentially serious illness causing vomiting and a bodily reaction against intake of food and liquids.

According to Celeb Dirty Laundry, Kate's mother-in-law, Camilla Parker-Bowles "doesn't consider hyperemesis gravidarum to be a serious illness, and she thinks that Kate is overreacting to a bit of morning sickness".

Adding on, the report said that, "Camilla has been dissing Kate for cancelling all her public royal appearances and Prince Harry's birthday party due to a touch of morning sickness, something Camilla thinks that Kate should just fight through."

Meanwhile, Prince William replaced Kate and attended the two-day event.

"I'm sorry you've got me instead of Catherine," he joked. "She's very disappointed she couldn't be here today."