Does Singled Out hold up?

Singled Out: How Two Million Women Survived Without Men After the First World War, by Virginia Nicholson (2007)

A social history of the women of Britain who did not marry after the First World War, drawn from letters, memoirs and interviews.

The short answer

Yes, with one qualification: 'two million' was the newspapers' round figure for the gap between the sexes, not a count of women who never married.

The claims, checked

Two million women were left without men after the First World War.

Holds with conditions The 1921 Census counted 1.72 million more women than men in England and Wales (1,096 women per 1,000 men). That counts every woman in excess of the number of men, including girls and women already married or widowed.

Evidence: Office for National Statistics, on the 1921 Census