The nation state, the construct that has dominated global politics and diplomacy for two centuries, can no longer meet the needs of citizens. This is the stark conclusion of a former high-flying British diplomat who quit the Foreign Office in disgust over Iraq and who has since worked with emerging governments in trying to assert themselves on the world stage.

Carne Ross takes up where Naomi Klein, Noreena Hertz and others left off. This is an impassioned, idealistic critique of the state of global politics and the deepening rift between those with power and those without. One of the book's strengths is that he seeks solutions, though I wasn't always persuaded of their effectiveness.

Most of all this is a mea culpa. It is refreshing for a non-fiction author to be so brutal about himself. Ross was one of an elite corps of diplomats, fast-tracked to a high position at a relatively young age. He would probably have received a top ambassadorship – with all the baubles of status and comfort that he admits he found attractive – had he not jumped ship.

As the lead official at Britain's mission at the United Nations in New York dealing with Iraq, Ross was responsible for implementing policy on weapons of mass destruction and the pre-war sanctions regime. He contends that the Brits and their allies knew pretty much all along that Saddam Hussein did not possess significant WMD. Therefore, in his view, the sanctions were unjustified punishment of a people who suffered widespread privation. Ross cites experts' estimates of an "excess mortality rate" of over 500,000 children under the age of five. "Though Saddam Hussein doubtless had a hand too, I cannot avoid my own responsibility. This was my work; this is what I did."

It is when people feel dissociated from the consequence of their actions that harm is done. The author recalls Stanley Milgram's famous laboratory experiment from the 1960s, which showed how easily humans could obey orders to torture, giving electric shocks to other participants. This, Ross argues, showed not just the pernicious effects of authority upon moral conduct, but something even more revealing: "the fact that the volunteers who administered the electric shocks, crucially, were told that they had no responsibility for the results".

At the heart of the corrosion of public life is the time-old relationship between politics, power and money. Ross details the pernicious influence of lobbyists, which he argues pervades Whitehall as much as it does Washington DC. While the argument is not new, the details are engaging. From McDonald's to Pepsi, from Kraft Foods to BP, rules were bent to accommodate corporate interests. I was particularly struck by the exemption granted to Wrigley chewing gum during the imposition of sanctions against Iran. The gum, Ross tells readers, "was classed as 'humanitarian aid' and thus exempt from sanctions, permitting millions of dollars of sales".

Yet, in its desire to cover the gamut of evil-doing, the narrative loses impact. One minute readers are taken to Kosovo, the next they are told about David Cameron's Big Society. Then from Iraq they are in US healthcare. Still, this is an important contribution to the debate. Ross bravely advocates the term anarchism (a positive absence of distant, top-down leadership), which he differentiates from anarchy, the absence of rules and the onset of chaos. He seeks a new form of engagement which borrows from the right an appeal to individual enterprise and self-expression, and from the left a sense of solidarity and community.

He concludes with a nine-point manifesto for citizens to regain control of the decisions that affect their lives. It includes: work out the priorities that affect you and pursue them; identify "who's got the money and who's got the gun" (in other words, where the power resides); do what you can when you can (for example, don't wait for asylum policy to improve); help an affected family (as his parents did first for a Czechoslovak student escaping the Soviets, and 30 years later for a Zimbabwean fleeing Mugabe).I am not convinced that they add up to a whole, but the individual parts are compelling.

It comes down to on-the-ground change. The most illuminating example Ross cites is the experiment conducted in Porto Alegre. In 1989 the Brazilian city was one of the most unequal in Latin America. It then embarked upon "participatory budgeting", with citizens encouraged to join debates about local spending priorities. Some 50,000 of its 1.5 million citizens take part. Apparently the number of schools has increased fourfold, while provision of sewerage and water is now comprehensive.

His message to the elite is that if they do not listen and act, they will face the consequences: "The less people have agency – control – over their own affairs, and the less command they feel over their futures and their circumstances, the more inclined they are to take to the street."

John Kampfner is author of Freedom For Sale and Blair's Wars