Marina Wheeler — a leading barrister — will become Sir Keir Starmer’s new whistleblowing tsar.
Ms Wheeler separated from ex-Prime Minister Mr Johnson in 2018.
The 59-year-old’s role will involve strengthening employment rights to protect women from abusive colleagues.
She said: “Women in the workplace too often suffer sexual harassment and assault and they pay a heavy price for speaking out.”
Her appointment will be confirmed in Shadow Attorney General Emily Thornberry’s speech tomorrow at the party’s conference in Liverpool.
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Marina married Boris in 1993 after they met again while he was working as a reporter for The Daily Telegraph.
The couple went on to have four children together, Lara Lettice, Milo Arthur, Cassia Peaches and Theodore Apollo.
Marina is Boris’ second wife.
His first marriage was to Allegra Mostyn-Owen, the daughter of the art historian William Mostyn-Owen and the Italian writer Gaia Servadio.
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The marriage was dissolved in 1993, six years after they wed.
BoJo is now married to the former Tory spin doctor, Carrie Symonds, with their two children, Wilfred and their new baby girl.