Princess Eugenie talks about "everything" with Princess Beatrice

She told Britain's HELLO! Magazine: "I ring her a lot about meltdowns and what we do and this and that. When I was Instagramming that photo, I rang her, and I was like, 'What do you want me to say?' Because I always want to ask, just in case. And she said, 'Can't wait to talk about the trials and tribulations of motherhood."

"I posted about our mothering journey, because it really is like you become part of a club - a mothering club. And when your children are the same age and they're going through the same things, it's just the luckiest thing in the world... And Bea's my big sister, I talk to her about everything!"

Eugenie is yet to explain to her own children that they have a new cousin on the way and thanks that the news might only become apparent once Beatrice's pregnancy belly starts to grow.

She said: "I haven't got that far yet. I think maybe Augie will see the tummy growing and realise but no, they don't get it. Just yet."

Eugenie is the daughter of King Charles' brother Prince Andrew and his ex-wife Sarah, Duchess of York, and is very aware of the "pride" that her mother has in her now that her two daughters have children of their own.

She said: "Mum's funny, because she loves her grandchildren so much but you can just see this pride for her two daughters.. she's like 'my babies!' When you become a granny you have the pride for the baby and your baby, you know? She's got a double whammy there!"