Mary, Madeline and Pamela Wyndham were "born into privilege's heartland".

The daughters of "a Tory of the oldest sort" and his Irish wife, they never lacked for money or opportunities, but this did not guarantee a happy life. Their childhood appears to have been rather lovely: one contemporary identified "an air of bohemian quasi-culture" within the family and Mary - the first to be born, in 1862, before the move away from rural Cumberland - had a girlhood "like a pre-Raphaelite painting brought to life". There was a darker side. The girls' mother, for all her outward calm and affection, sometimes sank into depression and anxiety, owing to "a mind seething with dread". On the whole, though, the troubles only really began when the girls grew up.

Mary married Hugo Charteris who, with his gambling and other assorted flaws, does not seem to have been the nicest of chaps. Pamela married the industrialist Eddie Tennant, and the two were hardly soul-mates. Stuck in a "mock baronial monstrosity" she spent most of her home life locked away in the library, only emerging to play with the children she adored.

Madeline fared much better. She loved her husband, Charles Adeane, deeply and seems to have relished her cosy country life and the conventionality it brought. Claudia Renton paints a pleasing picture of the newly-wed: "Perhaps the only hint of the bohemian roots of young Mrs Adeane was the pet fawn that followed her, like a puppy, everywhere she went." Not that Madeline avoided tragedy: after longing for a son, one was finally born prematurely and died within a day,

The thing about the Wyndham sisters, however, is that their public lives were every bit as important as their domestic travails. They were glamorous, extraordinarily well-connected, and stars of a gilded generation. One example of this is "'the Souls" - the "fascinating, chattering" social set which played a key role in the Wyndhams' story. The Souls was a group that included many of the era's most important politicians and cultural figures. All were well-to-do and the membership was "charismatic, mostly young, and unusually good-looking". They had their private lingo, flirted with each other a great deal, and measured their social success by how well their fellows did in public life.

Quite what went on at all the dinners and country house parties remains unclear. Activities seem to have ranged from innocent games to pushing the boundaries of accepted sexual behaviour. Mary, who was most closely involved with the Souls, later talked about relationships that were "a little more than friendship, a little less than love". What is certain is that the Souls were cliquey and pretentious.

In this outstanding book, Renton provides many insights into a crucial chapter of the era's social history. The number of luminaries who pop in and out of these pages is astonishing, from political bigwigs such as Arthur Balfour and Edward Grey (men with whom Mary and Pamela, respectively, had long friendships) to Oscar Wilde.

As for the sisters, one is inevitably tempted to choose a favourite. Madeline appears to have been the nicest, and Mary is probably the most interesting: the precise nature of her relationship with Balfour is intriguing. The laurels, however, go to Pamela. She saw through all the glitz and was both sharp-tongued and strong-willed. She was also demonstratively affectionate to her children, and various arch comments were made about the way she draped herself with the kids and carted them about with her whenever possible. This was just one pleasing symptom of her "regal indifference to convention".

She also did a good job of summing up the confusion and tragedy of the First World War, the event that shattered her and her children's generations. The first months of the conflict, she remembered, were like "the early morning, before the world was numb with pain and broken, before things were stale and tired as they became."

The Wyndhams' social class suffered as terribly as any other. As Renton explains, one in five of the British and Irish peers and their sons who fought in the war did not come home: the average fatality rate was one in eight. They were often the junior officers who led the charge, and were first to be mown down. It therefore becomes very easy to forgive the carefree pre-war antics of their mothers and fathers.