Boris Johnson’s baby revelation came just days after his ex’s mum died of cancer.
Marina Wheeler was mourning Dip Singh when he and fiancee Carrie Symonds broke the news.
The timing has been “devastating” for his grieving ex-wife, sources revealed.
The PM’s fiancee broke the news on Saturday that she was expecting and the couple had got engaged, days after Marina Wheeler’s mum died of cancer at 87.
Dip Singh passed away the previous Sunday, the Mirror understands. It is the latest trauma for Marina who, on top of her divorce, had two ops to treat cervical cancer last year.
A source said: “Dip used to be very supportive of Boris in the early years and refused to believe the bad stuff about him.
“Dip and [husband] Charles were very, very good to him.
“Boris and Marina’s wedding reception was held in their garden. Marina was very close to her mother who was enormously graceful and clever.”
Marina’s 25-year marriage to Mr Johnson, which was blighted by his serial affairs, formally ends in weeks.
A judge approved a financial settlement on February 18 and gave Marina the permission to apply for a decree absolute.
Marina married Mr Johnson in 1993 and the couple had four children. They announced plans to divorce in 2018.
Their eldest daughter Lara, 26, reportedly branded her father a “selfish b*****d” when news of his affair with Ms Symonds broke that same year.
A source had said of Marina’s health problems and divorce: “She’s just in pieces over it all.”
Mr Johnson had flings with a series of women. One gave birth to a daughter from him, now aged 10.
Dip was born in India in 1932 and fled her home in the Punjab aged 15 during the partition.
She married BBC foreign correspondent Sir Charles Wheeler in 1962.
The couple had two children, Shirin, 57, a former BBC correspondent, and Marina, 55. Charles died in 2008.
Barrister Marina confirmed Dip “died at home with us” but did not comment further.
She is due to publish a book about her mum’s life called The Lost Homestead.
Mr Johnson, 55, did not respond to our request for comment.