Katie Hickman's new book is a colourful and readable survey of the lives of British diplomatic wives from the 17th century to the present. The diplomatic life, she writes, "invariably brings to mind a vague impression of luxury - of diamonds and champagne, [and] while it is relatively easy to conjure with these fantastical images . . . it is much more difficult to imagine the reality behind them". Yet the reality behind that glamour is exactly what her book is about.

Daughters of Britannia reconstructs the lives of four dozen diplomatic wives, stretching from the Countess of Winchilsea, who arrived in Constantinople in 1661, to Susie Tucker, whose husband served in Prague and Slovakia in the 1990s. The broad range of sources includes archived letters and manuscripts, the British Diplomatic Spouses Association Magazine, and personal reminiscences (Hickman's mother, Jennifer, was married to a diplomat who served in New Zealand, Dublin and Chile). The material is arranged by theme rather than by person - chapters are titled "Private Life", "Hardships" and "Rebel Wives" - a structure that doesn't so much suggest progressive change in the lives of diplomatic wives, as illuminate, intriguingly, how the patterns of those lives have remained much the same even in contrasting eras.

Dotty wives are a case in point. British diplomatic wives - ambassadresses, in particular - have long been notorious for their madnesses. Lady Cumming Bruce, ambassadress to New Zealand, would arrive at receptions wearing her bedroom slippers. Ella Sykes, sister of the British consul to Kashgar in the 1910s, climbed the 12,000-foot Terek Dawan pass wearing a pith helmet, a gauze veil and a pair of blue, glass goggles. Lady Elgin cross-dressed to attend her husband's audience with the Sultan, a dangerous venture in early 19th-century Turkey.

More insidious were the so-called "dragon" ambassadresses, who dictated attire, behaviour and other matters of etiquette to their inferiors. In Paris, sedatives were prescribed to two embassy wives whose mental health was suffering on account of being forced to entertain constantly.

From the material Hickman has collected here, however, it's clear that many of these madnesses may have been reactions to the demands of diplomatic life. Travelling between postings in 19th-century Persia, Elizabeth McNeil lost three of her four children. Miss Tully, a relative of the British consul to Tripoli in the late 1700s, lived through the bubonic plague by spending 13 months quarantined inside the Tripoli consulate. "The cries of the people for the loss of their friends are still as frequent as ever," she wrote to a friend in 1785.

When Mary Fraser arrived in Hong Kong in 1874, in the wake of the worst typhoon in 50 years, the harbour was awash with floating bodies. And when Geoffrey Jackson was kidnapped by Uruguayan terrorists in 1971, his wife, Evelyn, told the Uruguayan foreign minister that there was to be "no exchange of prisoners, no ransom and no negotiations" - a policy she felt would kill her husband - because "that was what Geoffrey wanted, and I was his wife, and that was my duty". Fortunately, he lived.

Even in less troubled times, life was seldom easy for diplomatic wives. As representatives of Britain, their dress and behaviour were under incessant scrutiny. They had to learn complicated and often arcane codes of behaviour. In 1880s Washington, Victoria Sackville mastered the complexities of the calling card. A married woman was to leave three cards - one of her own and two of her husband's - when visiting a married woman, but only one of her husband's cards when visiting a single or widowed woman, and none when visiting a man, while a bachelor or married man would leave two of his cards for a married couple, but would never leave his wife's card.

Vita Sackville-West, in a letter to Virginia Woolf from Tehran in 1926, captured the drudgery (and indeed absurdity) of these ritualised lives. "Compound life means that at 8am the consul's son, aged 10, starts an imitation of a motor horn; that at 9am somebody comes and says have I been letting all the water out of the tank; that at 10am the military attache's wife strolls across and says how are your delphiniums doing. Correctness is the order of the day, so we never get any further." Small wonder, then, that so many wives disliked the overwhelming formality of it all.

Daughters of Britannia isn't merely a defence of diplomatic work. Hickman's point is that the unpaid work of the wives was central to the diplomatic endeavour. "In no other profession has a wife been so intimately involved with her husband's work," she writes. "Diplomacy has always depended on the quality of its human relationships, and the social life which helped to foster them was serious business." So getting dressed and leaving calling cards was an essential part of diplomatic business. The accounts that these wives offer are more than small anecdotal tales of domesticity; they are an integral part of the history of diplomacy itself.

It's a compelling idea, and one that seems particularly relevant in an era when e-mail and other communication and travel technologies render traditional diplomatic functions obselete. As the symbolic roles of diplomats increasingly supersede their political work, so it may just be that the predecessors of today's diplomats are not the men who held office, but diligent hostesses such as Miss Tully and Ella Sykes.