To come across dates and names carved into a choirstall or ancient tree is to experience a momentary frisson, a startled connection with the past. Yet this practice of making ‘unauthorised’ personal graphic statements in public spaces is often thought of as antisocial, something to be erased immediately. Unless of course they are by Banksy, whose spray-painted outpourings cost local councils a great deal to clean off before they came to be regarded as valid documents, articulating the thoughts and imaginings of the disaffected.

In her ingenious new book Writing on the Wall, the art historian Madeleine Pelling has chosen to use these often transitory pieces of historical evidence as a way of illustrating the huge cultural changes that took place in the 18th century. In this ‘library of irresistible and ephemeral objects’, she argues, we can find perhaps a more accurate understanding of that extraordinary century of change. The ‘so-called Enlightenment’ was forged by ‘the inky fingers of seditious printers, loquacious orators and… provocative graffitists’.

But graffiti is a slippery thing. So much is lost and wiped away almost as soon as it is created. What is left does not necessarily provide us with an accurate picture of what has gone before. Pelling has also set herself the problem of creating a coherent narrative out of random records with no real link between them other than the human desire to make something that will both outlive us and connect us to the future.

She begins with the Gordon Riots of June 1780 when, nine years before the French stormed the Paris Bastille, thousands of enraged Londoners overran Newgate Prison, freeing those inside and setting much of it alight. For days the city was on fire, terrified observers trapped in their homes while the rioters marauded through the streets, daubing ‘No Popery’ on the doors of buildings they suspected were occupied by Catholics. This, suggests Pelling, was the moment that graffiti became political, developing ‘a bold language of protest’ that was written across the great institutions of power, such as the monumental walls of the Bank of England.

Already, though, during and after the dramatic events of 1745, when Bonnie Prince Charlie and his rebellious army advanced as far south as Derby before turning back and ending all hopes of a restoration of the Stuart monarchy, ‘45’ had been daubed all over London and beyond. In John Collet’s cartoon of 1771, ‘The City Chanters’, a young boy is shown chalking ‘45’ on to the coat of a bewigged lawyer.

Other artists, such as William Hogarth, show us just how compulsive this need to make a mark has always been. In the first of his ‘Four Stages of Cruelty’ from 1751, documenting the thuggish behaviour of Tom Nero, from abusing a dog to full-scale murder, a man is shown alongside Nero, drawing on a blank wall a gallows with a figure hanging from it. For Hogarth, graffiti is moral lesson: it provides a channel for opinion, the voice of the underdog.

Hogarth’s success was dependent on the development of cheaper printing techniques and the book trade. As early as 1731 this had made possible Hurlothrumbo’s publication of a random selection of graffiti found in the taverns, coffee houses and privies of London. The Merry-Thought; or, The Glass-Window and Bog-House Miscellany gives us a rich variety of cheesy one-liners and bawdy rhymes noted down from walls and panes of glass. ‘Here did I lay my Celia down; I got the P-x, and she got half a Crown’, for example. Or ‘There’s nothing foul that we commit, But what we write, and what we sh-t.’ How much these lines owe to the creativity of Hurlothrumbo is not known, but in Daniel Defoe’s Moll Flanders, Moll and her lover carve messages to each other on a pane of glass in her bedchamber, suggesting the practice was widespread.

Most haunting are the ships, nautical knots, dates of arrival and names carved deeply into the walls of Portchester Castle by the hundreds of prisoners of war brought there after the revolutions in the Caribbean of 1796. Or the cityscape on the wooden panelling of the Wellclose Prison, now in the Museum of London, etched by a debtor incarcerated in the 1720s.

Pelling ends her book with a quotation from the 17th-century poet George Herbert: ‘A white wall is the paper of a foole.’ It’s an odd ending for a book whose flashes of insight are often obscured by the heavy weight of cultural analysis: ‘These fragments of the past could, in the present, confirm or tear down authority, bolster political allegiances and colonial projects and even justify racial hierarchies as set out by white Europeans.’

The power of writing on the wall lies in its immediacy, its individuality and its specificity. To come across ‘ROUNDHEADE 1645’ carved on the side of a marble tomb in a Norfolk church is to witness the past in just one word and a single date.