The Gavin and Stacey actress revealed her news on Twitter telling her followers:  “Happy news! James + I are delighted to announce we’re expecting a baby! X.”

James, 36, known best for his role in Emmerdale, then followed suit, tweeting: “Happy news! Jo + I are delighted to announce we’re expecting a baby! X.”

The couple have been married for nine years, and only last year the 34-year-old actress, who also starred in the 2003 film Love Actually, spoke of her desire to start a family.

Speaking to the Telegraph, she said: “Careers, when they take off, can take your mind off babies temporarily, but I think it always comes back to when the time is right.”

She also joked in the interview that she didn’t think she’d be a very “glam” mum, saying she’d : “probably be the sort who in the first week would be baking all of the cakes and then would be down the supermarket buying stuff and passing it off as my own.

“I’d also be the type who turns up with her hair in ponytail, no make-up and still in pyjamas. I wouldn’t be very glam.’

After their pregnancy announcement, the couple’s Twitter pages were flooded with goodwill messages.

Tom Ellis – Joanna’s co-star in Sky comedy Gates – wrote: “zipedeedoodah zipedeeday… congrats to you both… if you need any tips don’t ask me. I’m still trying to work it all out! Lovage xx”