Down a small alley off Whitechapel High Street, a short walk from London's financial district, sits Britain's oldest radical bookshop. Founded by Peter Kropotkin and Charlotte Wilson in the 1880s, Freedom Press has been a hub for the city's counterculture ever since – a pick-up point for campaign materials, a meeting space for activists and a printer of radical literature, as well as a bookseller.

But my visit is not on a normal day. In the small hours of the previous morning, an attacker had forced open a shutter, broken a window and set the inside alight. Next to the broken glass is a shelf full of volumes on George Orwell – perhaps Britain's most-quoted opponent of book-burning. The fire and water leaves his image distorted and charred. The books are reduced to an inseparable block of pulp.

A throng of volunteers has gathered for the clear-up. Some are anarchists; others are showing solidarity with a group that has for so long shown solidarity with others. The atmosphere is somehow both cheerful and defiant. There is a human chain carrying salvageable books up the stairs. As there seems to be quite a queue forming, I join the other group, tasked with the soul-crushing job of picking, cataloguing and disposing of the books that are damaged beyond repair.

We organise ourselves into sorters and cataloguers, the latter of whom playfully get called the bureaucrats. "Hey, bureaucrat, I've got five copies of Thinking Housing here – can you note that down?" "Bureaucrat, are you listening? Five Anarchy in Actions." Becoming aware of the managerial system we are inadvertently mimicking, we decide to change tack and buddy up, rotating roles. No more bureaucrat-worker divide. As it turns out, it's more efficient, too.

In a way it is cheerfulness born of necessity. The job of noting down books for the scrapheap is a sad one. The camaraderie is the only alternative to tears as we clock up 300, 400, 500 volumes. The unsavable ones are taken away in sacks.

In their place come cake and tea, then hot food. A bike-powered sound system pumps out funk tunes. Then there's a cheer across the building, as the electrics flicker into life. There's a call out: "Does anyone need a job?" followed by a wry chuckle and a movement into the backyard of yet more people who have recently arrived, to start cleaning shelves.

The pile finished, I head upstairs. It is an altogether happier scene. Thousands of books are piled from floor to ceiling: Zapata of Mexico, Mutual Aid, a history of Anti-Fascist Action. Squeezed around the edge are tens of people, with standing room only, cleaning cloths in hand, scrubbing, chatting, restoring and ruminating. Instead of the choking stench of ash that overwhelms the rooms downstairs, the fresh odour of cleaning spray fills the air. One by one, the books are lovingly relieved of their sooty second covers and returned to their former glory. The items destroyed are just a fraction of those that remain.

Three hours later, the shop has been transformed. Everything has been removed, the fire-blackened walls are being cleaned, and staff predict they will open again on Monday. Sixty volunteers with no discernible leader have pulled off an awe-inspiring display of self-organisation.

If the attacker's plan was to make important ideas disappear down the memory hole, it looks as if it has backfired spectacularly. As the clean-up operation shows, there is more than one way to encounter an idea. One is to read about it. But wholly more powerful is to experience it. And so it is today that written concepts are lived in reality and anarchy is demonstrated in action.

• This blogpost first appeared on the New Internationalist website