In 1975, supposedly one of the worst years of supposedly the worst decade in recent British history, voters chose to remain in the European Economic Community, now the European Union, by 67.2% to 32.8%. Britain was more insular, more racist, less cosmopolitan, and less confident than it was when the next referendum on Europe was held, 41 years later. But even in Essex and Lincolnshire, the Brexit heartlands of the future, support for Europe was overwhelming. Neil Kinnock, who like many on the left campaigned for leave in 1975, told the Western Mail: “Only an idiot would ignore or resent a majority like this. We’re in for ever.”

Britons preoccupied with the EU, whether for or against, often prefer to invoke history in the abstract rather than actual historical facts, and making sense of the apparent mysteries and contradictions of the 1975 referendum is a task few authors have attempted. Before this thick book, the standard texts were volumes published in the 70s. Robert Saunders’ aim is to look at the contest afresh, in the light of the 2016 referendum, and to use the 1975 campaign “as a window into the political and social history of the 1970s”.

Any fears that this might be a slightly dutiful project – a purely academic raking over of a brief Europhile moment – are quickly dispelled. Saunders writes with swagger rather than dryness. He describes the prominent leaver Tony Benn and equally prominent remainer Roy Jenkins debating on television in 1975: “the baroque courtesy of two men with murder in their eyes”.

With an efficiency that feels almost gleeful, he demolishes many of the myths about Britain’s relationship with the rest of Europe on which Brexiters and remainers have long depended. Far from being free and independent, or parochial and isolated, before joining the EEC in 1973, Britain was already “more closely involved with the continent than at any previous point in its modern history”, through membership of bodies such as Nato and the Council of Europe. Similarly, once the 1975 referendum campaign got under way, the consequences for British sovereignty of further integration into Europe were not covered up, as Brexiters often insist. “Slogans like ‘the right to rule ourselves’ were blazoned across anti-Europe literature,” Saunders records. “Sovereignty was … the theme of almost every speech by Tony Benn and Enoch Powell”, the other divisive figure at the head of the leave campaign.

The EEC was also seen as strongly pro-capitalist: significantly, Britons called it the Common Market

Refreshingly, Saunders generally manages not to take sides. But touchy Brexiters may sense a patronising undertone in some of his urbane descriptions. The leave campaign “operated out of two rooms near the Strand and employed just three full-time staff”, he writes. To call it “a skeleton operation would overstate its solidity and coherence”.

The remain campaign had no such difficulties. “Cars, aeroplanes, helicopters, film units, stage equipment, photocopiers ... simply appeared at a flick of [the] fingers,” recalls David Steel, one of remain’s immense array of centrist politicians, celebrities and business leaders. Unlike in 2016, the pro-European establishment used its resources shrewdly, combining a negative campaign – warning that a leave vote would be economically catastrophic; attacking Benn and Powell as extremists – with carefully targeted advertising about the concrete benefits of EEC membership.

The remainers had other advantages, some of them startling from today’s perspective. Every national paper except the Morning Star supported them. For many journalists, EEC membership was still an intriguing novelty. Margaret Thatcher, then a new Tory leader, supported it. The EEC was seen as strongly pro-capitalist: significantly, Britons called it the Common Market. This was precisely why some leftwingers wanted Britain to leave. Saunders includes enthusiastic quotes from the Tory tabloids about the referendum result – “louder, clearer and more unanimous than any decision in peacetime history,” roared the Express – that ought to embarrass their proudly anti-EU editors now.

Britain’s erratic mid-70s economy meant that EEC immigration was minimal and largely uncontroversial. There were fewer arrivals in the whole of 1975 than in an average week in 2016. Saunders describes anxiety about the country’s prospects hanging over the referendum. He quotes an anonymous young man from Altrincham: “We’ve got to stay in. This country will sink without trace if we don’t.”

As a portrait of Britain in the 1970s, this book is disappointingly traditional. There is the usual emphasis on national crises, tackiness, sexism – “Europe or Bust” on women’s T-shirts. There is little on the huge counterculture, the era’s unprecedented economic equality or the rising radical left. Jeremy Corbyn, by 1975 a well-known north London socialist, does not feature (he voted leave).

Others outside the political mainstream were not interested in the referendum. Voter turnout was 64.5% – much lower than for 70s general elections. As a measure of the state of the nation, the referendum was limited, like its 2016 successor – as the 2017 election revealed. But as a study of a rare and seminal event, this book bursts with valuable details. One of the best comes at the end. “Within days” of the referendum result, Saunders writes, the leavers began their long campaign to overturn it. There might be a lesson there for remainers.

• Yes to Europe! is published by Cambridge University Press. To order a copy for £21.24 (RRP £24.99) go to guardianbookshop.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min p&p of £1.99.