It comes at a hard time for the family, after James’s father, David, 74, was accused of rape.
Kate, only weeks away from giving birth to her third child, was the first person after Pippa’s husband, James Matthews, to hear the good news.
The announcement comes weeks after James’ younger brother, former Made In Chelsea star Spencer Matthews, 28, and his 32-year-old fiancee, model Vogue Williams, confirmed they were expecting their first child.
Pippa was said to be excited to start a family after marrying financier James in May last year.
Eight months pregnant Kate, 36, kept an eye on Prince George, four, and two-year-old Princess Charlotte, who stole the show as page boy and bridesmaid.
The baby is due in October.
The news comes after it emerged James and Spencer’s father, 74, was being investigated over allegations he raped a minor.
He was questioned in March by French police over an attack, said to have happened between 1998 and 1999, and placed under investigation by a magistrate.
This month, it was revealed a second woman had made similar claims against him, this time dating back to the 1980s.
He denies the allegations, labelling them “untrue and scandalous”.read more