The Bridget Jones's Diary star admits in her upcoming autobiography The Happy Hoofer she never wanted to settle down with a man, but longed for a child.
Imrie told Whitrow about her plight in the early 1990s and he offered to father a child with her. The actress accepted - but the 58 year old was clear in her conditions for the deal.
In the book, she writes, "I told Ben that, although I never wanted to take that step (marriage), I did want a baby, now more than ever, before it was too late. Ben asked if I meant it. We gradually got to know each other and grew very fond. He thought perhaps in time... But because Ben had a grown-up family I was very anxious not to upset them.
"Ben and I walked on the beach one day as I laid out my terms. As long as he understood I would not ask for anything, I wouldn't want to live with him, or marry him, would never ask for money for the child and I would be responsible for choosing and paying for the child's education, accommodation, clothing - everything. If Ben could take all that on board, I said, then his offer to fulfil my wish for a child would be wonderful."
Imrie gave birth to a son, Angus, in 1994 - and now admits Whitrow has become a male role model in the teenager's life.
She adds, "He has proved to be a marvellous father to Angus. And his whole family has been very welcoming."