Clementine Ogilvy Spencer-Churchill, Baroness Spencer-Churchill, (née Hozier; 1885 – 1977). Wife of Winston Churchill and mother of Diana, Marigold and Sarah Churchill.
We found only one reference to her having red hair. In this book, the
photo below is captioned "The Liberal-minded. red-headed Clementine
Hozier in 1915 after she married Winston Churchill."