The Woman Who Shot Mussolini, By Frances Stonor Saunders

At least four people tried to assassinate Benito Mussolini, but the Honourable Violet Gibson, child of a rich and prominent Anglo-Irish family, was the only one to draw blood. She travelled to Rome with the original intention, it appears, of murdering the Pope, but then changed her plan. On 7 April 1926 she took her revolver and a stone wrapped in a cloth (for use in case she needed to smash the window of his car) and walked to the Campidoglio, Michelangelo's magnificent piazza. There she shot the Italian prime minister at close range. Her first bullet nicked his nose, drawing copious blood; the second jammed. She was set upon by the furious mob and only saved by the police from being lynched.

It was, in effect, the only thing she did in her long life. It made her an instant celebrity, though with none of the acclaim that might have accrued if she had shot him in 1935, when his threats to invade Ethiopia forced a radical revision downwards of the opinion of the man who had made Italy's trains run on time; let alone in 1938, after the passing of the notorious Race Laws stigmatising Jews, or in 1940, when he declared war on France and Britain. Violet had the misfortune to be well ahead of her time in her view of the Italian dictator; and to be crazy.

Was she? Frances Stonor Saunders lets the record speak for itself. There is little doubt that she was, at least some of the time. Raised as a staunch Dublin Protestant when an Irishman's views on transubstantiation were the index of his station in life, she came from a generation of Gibsons who fled to the four winds, spiritually speaking, as the struggle for Irish independence gathered pace. Her elder brother Willie, heir to his father's title, became a Catholic and a Home Ruler and was disinherited for his trouble. Her mother and a sister became Christian Scientists, while Violet had a lengthy flirtation first with Madam Blavatsky's Theosophy then with Rudolf Steiner's Anthroposophy, before following Willie into the Roman fold.

The mix of spiritualism, mysticism and Catholicism proved highly combustible for Violet, who discovered a religious vocation which required her to make a sacrifice, not of her own life but other people's. Once she had decided that Mussolini was the man God wanted her to kill, she planned the deed methodically, sending her Irish companion back home to be out of trouble, plotting Il Duce's movements, and keeping her plans well hidden from the Roman convent where she was staying, on high alert after she had attempted to kill herself with a different revolver the previous year.

For a year after the murder attempt, Violet's fate hung in the balance as she shuttled between prison and mental hospital. But the smooth British ambassador Sir Ronald Graham, who had built an excellent working relationship with the man Westminster regarded as "a statesman of exceptional ability and enterprise" (in Graham's words), persuaded Mussolini to get his new Special Tribunal to acquit her on grounds of insanity, and to expel her on condition – never spelled out to Violet – that she would be put into a British lunatic asylum and never allowed out.

And so it came to pass. She was committed to the expensive private home in Northampton where, despite numerous attempts to get herself moved to a convent, she remained until her death nearly 30 years later, forgotten by the world and neglected by her family. It is a depressing story, garishly lit by one mad deed. Yet in the author's hands its very blankness makes it a bright mirror for the cruelty, cynicism and official lunacy of the recent past.

Mussolini had just as good a claim to be mad as his would-be assassin; the British diplomacy that heaped him with praise was merest common sense at the time but looks delirious now. The terms of the deal to bring Violet home were understandable, given that she remained sporadically violent for years, lashing out with a hammer or a broom.

But with her treatment by the expensive hospital, the story comes right up to date: dozens of letters she wrote unposted; perfunctory and downright delinquent medical attention; the routine rejection, possibly on commercial grounds, of her pleas to be moved, and finally the brutal ignoring of the desire in her will for a decent tombstone and a Catholic burial. Nothing mad about any of that – just plain old English indifference. It chills to the bone.