Giovanna Fletcher says Duchess Catherine was "as nervous as she was" when they met up to record her podcast.
The 'Happy Mum, Happy Baby' star met up with the 38-year-old royal - who has Prince George, six, Princess Charlotte, four, and Prince Louis, 23 months, with her husband Prince William - to discuss motherhood and the London Early Years Foundation.
She said: "Needless to say I had a few sleepless nights of worry and panic in the run-up. I always say that we need to look at what unites us in parenting, that it doesn't matter who you are, what you have or what you do - we're all facing many of the same battles with our kids. Yet, the fact she is raising a future King obviously wasn't lost on me. In fact, it was only when I started thinking about the questions I would ask in the episode that I started to regain a sense of control. Outside all the fluff and noise, this was ultimately a conversation between two mothers. Well, I thought to myself, I can do that! We recorded the episode in a nursery in Stockwell, south London, in January, following a royal engagement together, where we chatted to staff and parents before dishing out breakfast to some of the children. Kids are always a fab ice breaker, and it's thanks to them that the duchess and I were having a giggle as we walked into the recording - particularly as one little girl had renamed us Daddy and Mummy Pig. And it turned out Kate was as nervous as I was."
Giovanna admits the Duchess of Cambridge was a "dream guest".
Speaking to The Sun on Sunday's Fabulous magazine: "From series one of my podcast Happy Mum, Happy Baby, I've had one dream guest - the Duchess of Cambridge. My first request was turned down when she was suffering with bad hyperemesis, and the second when her schedule was particularly busy. However, by now aware of my passion for opening up conversations around motherhood, last year Kensington Palace asked me to talk about the duchess' passion for early years."