Rory Stewart is one of that almost extinct species in the modern Conservative party, a one-nation Tory. He is also – or was (until Boris Johnson kicked him out) – a politician with hinterland. He had been places and done things before getting himself elected in his late thirties, entering parliament in 2010. Disillusion rapidly set in:

Too much of our time was absorbed in gossip about the promotion of one colleague or the scandal engulfing another. Even four weeks in, I sensed more impotence, suspicion, envy, resentment, claustrophobia and schadenfreude than I had seen in any other profession.

It is made clear to him from the outset that rebellion was fatal to ambition. Early on, David Cameron comes up with a daft plan to abolish the House of Lords and replace it with an entirely elected second chamber. Stewart was proposing to vote against. Minutes before the vote he is intercepted by George Osborne:

‘Rory, I am going to promote you to be a minister in ten days, but if you walk through that door,’ he said, indicating the ‘no’ lobby, ‘you will, I promise, not be promoted in the rest of this parliament. You will be a backbencher for at least five years.’

Stewart duly walks through that door.  Osborne is as good as his word.

Not until Theresa May becomes Tory leader does the author find himself in government. Over the next four years he holds no fewer than five portfolios in four departments, with responsibilities as diverse as flood control, prisons, overseas development and as Africa minister in the Foreign Office. It is part of the madness of government that he is rarely left anywhere for longer than a year. When he finally reaches the cabinet, as secretary of state for international development, he lasts just three months.

He enters each department fizzing with energy and ideas, only to find a distinct lack of enthusiasm on the part of most officials, many of whom seem to see him as an inconvenient irritant. On his first day at the DfID, a senior official actually suggests that he might use the department for his own ego trip.

I stared at her. She stared back. I did not trust myself to speak… But at the same time I was grateful for her response, for it had revealed more about how a senior civil servant viewed a minister than I might have picked up in a year.

He questions an aid programme to an area of northern Syria which, he points out, was controlled by jihadis. Officials, however, are in denial. When he insists on alerting the prime minister, his letter is edited to omit the key point. Eventually he goes to see the prime minister in person and the programme is quietly dropped.

His next port of call is the Foreign Office, under the chaotic stewardship of Boris Johnson. Stewart quickly comes up with a master plan for hugely expanding the British presence in Africa (goodness knows where he hoped to find the funding). Johnson appears unequivocally to approve: ‘Splendid, go for it, Rory.’ No sooner is Stewart out of the door than the permanent secretary explains that the secretary of state’s endorsement must be taken with a huge pinch of salt, ‘on the grounds that he likes to agree with the last person he had spoken to – even if this contradicted his previous instructions’. It is a tantalising glimpse of what lies ahead.

Later, during his brief tenure as secretary of state for international development, Stewart finds himself on the National Security Council, dominated not by ministers but by the military and intelligence top brass. He concludes, as some have long suspected, that civilian influence over the security establishment is, to say the least, tenuous. ‘The lack of knowledge among my political colleagues, the complexity of the subject and the opaque committee structures meant that there was little I would have recognised as civilian control and accountability.’

The book’s final chapters are taken up with an inside account of the leadership election which followed the downfall of May. In the absence of any candidate willing to publicly oppose a no-deal Brexit, Stewart boldly steps up to the plate and does surprisingly well, though ultimately, of course, he is a fish out of water in the modern Tory party. He watches in dismay as rival candidates solicit votes, shamelessly promising unfunded tax cuts, and as erstwhile Remainers morph into Brexiteers before finally, despite private misgivings, falling into line behind Johnson. 

This is a significant book – candid, beautifully observed, written by someone with a questioning intelligence and a burning desire to make the world a better place. Stewart might have been at home in the Conservative party of Harold Macmillan or Edward Heath but instead, alas, he is destined to remain a perpetual outsider.