I have always taken Lady Astor with a pinch of salt. This biography makes me think I would need a full salt-cellar. Adrian Fort is clearly intrigued by his subject and admires her considerable panache, but he is not seduced by her much-vaunted charm. She was one of those people – Scarlett O’Hara comes to mind in popular fiction – whose egoistical instinct to dominate and to be centre-stage is so enormous that others often mistake it for benevolence. The benevolence was largely dispensed by her somewhat overshadowed husband, Waldorf Astor, grandson of the founder of the dynasty, John Jacob Astor, and one of the richest men in the world at the time. It is hard to think of Nancy Astor, the society hostess, functioning without a million pounds at her disposal.

Perhaps this requirement arose from her colourful and impoverished background as the daughter of a notable Virginia family that was left adrift after the American Civil War. Fort makes a few guarded comments about her early life: “At no time in her childhood or youth was her intellect successfully trained or disciplined”; “apt to speak without thinking”; a “tendency to self-assertion”; “restless energy and increasing lack of inhibition.” These remarks tell us quite a lot between the lines. By the time this energetic, “wilful and often pugnacious” young woman, with her “increasingly sharp sense of the ridiculous” burst on the scene of sedate Edwardian London she was quite ready to take it by storm – despite being a divorcee with a young son. The grande dame of the time, Lady Desborough, soon found her own courtiers at Taplow, next door to the Astors’ Palladian mansion, Cliveden, had become magnetised by her younger American rival.

Born in 1879, Nancy met Waldorf in 1905 and they married in 1906. They quickly turned Cliveden, a wedding present from his father, into a centre for entertaining important and influential persons in the arts and politics. Waldorf, a quiet, intelligent man with a social conscience who wanted to play his part in the betterment of society, enjoyed the conversation of the politicians he gathered together; Nancy revelled in the power she exerted over the whole company: husband, friends, servants and children. Even though she had a high-minded concern for the lower orders in general, the staff at Cliveden suffered the usual lot of the servant class: long hours, low wages and cramped, damp accommodation.

Nancy was also something of a puritan. She hated alcohol, having seen what it had done to her father and her first husband; she frowned on gambling; as for sex, she would comment that her six children were “conceived without pleasure, born without pain.” This last might be to do with her discovery of Mary Baker Eddy, founder of Christian Science, in 1913; she instantly decided to become a Christian Scientist and subsequently employed her imperious mind over matter to dispel for good her various nervous complaints.

Her claim to fame lies largely in the fact that she became the first woman MP to take her seat in the House of Commons. Taking over her husband’s seat at Plymouth when he found himself unwillingly ennobled as the second Viscount Astor, Nancy’s “self-confidence, wealth, excellent staff support and the experienced guidance of her husband, exactly met the needs of the hour”, according to her biographer. On her speeches in Parliament, others commented that “she could not resist the temptation to moralise and she seemed to leap from idea to idea, often barely connected.” Unable or unwilling to master the rules of the House, she would generally stage her entrance noisily, make loud remarks over others’ speeches, walk up and chat to the Speaker, talk at random, ignore the arguments being debated and then sail out of the chamber again, having satisfied herself that she had played an important part in the proceedings.

By this stage the Astors were employing 150 servants, deployed around their various houses. Apart from their main mansion, Cliveden, they bought a large house in the best part of the Plymouth constituency; Nancy then built a seaside “cottage” with 15 bedrooms in Sandwich, Kent for occasional holidays; being involved in politics demanded the purchase of a grand London house in St James’s Square; and there was also an estate in Scotland where Waldorf liked to shoot in season. Lady Astor had much on her hands quite apart from any parliamentary work.

Fort comments that in middle age she “began to display a slightly unappealing selfishness”. Several pronounced prejudices came to the fore: Nancy disliked “socialism, Roman Catholicism, psychiatry, the Jews, the Latins and the Observer newspaper” (which her son, David, was later to edit.) Unwilling to let her adult children lead their own lives they, like others, found their mother controlling, difficult and demanding. On her deathbed she enquired, “Am I dying or is it my birthday?” Her son Jakie answered truthfully but with tact, “A bit of both, mother.”

She is fun to read about – but not a person with whom one would wish to cross swords (or paths).

Francis Phillips writes from Buckinghamshire in the UK.