In her new memoir, Bedsit Disco Queen, the pop musician Tracey Thorn bristles at how the decade in which she first became famous is lazily remembered. “Scenes which I never witnessed in my life – yuppies chugging champagne in City wine bars, toffs dancing in puffball skirts to Duran Duran – have now become the universal TV shorthand used to locate and define the era,” she complains. Thorn’s book is in part an alternative history of the 1980s: one populated by political rallies, “Meat Is Murder” and “Dig Deep for the Miners” badges, benefit gigs and literate musicians with an Indie DIY aesthetic like herself worrying perpetually about not “selling out”.

A new, publicly available digital archive just released by the University of Sussex, Observing the 1980s, aims to give substance to this subterranean history and helps to free the decade from the simplifications of popular memory. Among other resources, it brings together contributions by the volunteers who wrote about their daily lives for the Mass Observation Archive in that decade. The attitudes of these writers seem more passionate and polarised than we are used to today. “The Tories will get in again and if we were ten years younger we would emigrate,” writes one Mass Observer on the eve of the 1987 election. “The appeal to greed and self-interest, which characterises the approach of the Tories, is disgusting bordering on the evil,” declares another.

The archive also includes a selection of 1980s ephemera, mostly radical pamphlets about travellers’ rights, the Poll Tax or the “assault on the unions” created, in the days before desktop publishing, with typewriters and Letraset. They are a reminder that much of the radicalism of the 1960s survived into the 1980s, alongside a brief flowering of countercultural creativity and political activism among students (in the last age of full maintenance grants) and the growing ranks of unemployed people.

Here, in place of yuppyish hedonism, we find a moral and political earnestness that is alternately funny and touching. In 1987, for instance, the alternative newspaper the Brighton Voice gave a platform to a “men’s anti-sexist group” with a strict code of behaviour aimed at not intimidating women in public, including “wear bright clothing so you can be easily seen – do not creep around in silent footwear” and “carry a paper or magazine on public transport so you have somewhere to put your eyes”.

Thorn recalls her own fixation on remaining politically “authentic” with a mixture of fondness and bafflement. When asked by the teen pop magazine Smash Hits in 1985 about the last book she had read, she told them: The British in Northern Ireland: The Case for Withdrawal. When, she wonders, did this ideological intensity disappear and everything had to be seen instead through an “ironic tinge”?

There are whole books still to be written about this collective mental shift. But Lucy Robinson, one of the historians involved in the Observing the 1980s project, hints at one reason when she points out that this was the last decade before the internet. The Google search gave us a way in which we could skate over the surface of cultural and political life, slickly knowing a little about a lot of things. Perhaps it also gave people an internal edit button as they feared guileless or undeveloped ideas could be shot down quickly by internet flaming. Nowadays, an unusual book choice for a teen magazine might be ridiculed in an avalanche of Twitter retweets.

We like to give decades a uniform character as they retreat into history, safely burying the past by turning it into retro kitsch. The Observing the 1980s project is valuable because it does not treat the decade like this, as a story we already know the ending to. Instead it becomes an era of still-to-be-decided tensions and possibilities – one in which people sincerely people that David Steel might be prime minister (“my pin-up!” says one Mass Observer), that Margaret Thatcher might lose an election, or that the neo-liberal economic revolution might still be reversed. How I miss that sense of earnestness – and I mean that without a trace of irony.