A STONE’S throw from where I live in Glasgow’s Merchant City lies the Saltmarket. One of the city’s most venerable streets, it was originally home to the “fullers” – scourers of woollen cloth.

In the mid-18th century it was the place to hang out, the Dear Green Place’s equivalent of Bond Street or Saint-Germain. A hundred years later, however, it had changed utterly. As the population expanded at an alarming rate – it increased more than tenfold in a century, from 30,000 in the 1750s to 400,000 in the 1850s – the Saltmarket and its environs were transformed into overcrowded, insanitary, noxious slums with all the attendant social ills that suggests.

In 1842, a government report spelled out the scale of the problem as ever more people flooded in from the Highlands and Ireland: “In the very centre of the city there is an accumulated mass of squalid wretchedness, which is probably unequalled in any other town in the British dominions. In the interior part of the square, bounded on the east side by the Saltmarket, on the west by Stockwell-street, on the north by Trongate, and on the south by the river, and also in certain parts of the east side of High-street ... there is concentrated everything that is wretched, dissolute, loathsome, and pestilential. These places are filled by a population of many thousands of miserable creatures. The houses in which they live are unfit even for sties, and every apartment is filled with a promiscuous crowd of men, women and children, all in the most revolting state of filth and squalor.”

These words, written by a superintendent of police, are undoubtedly powerful and evocative but actually to see what life was like back then we need to turn to the photographs of Thomas Annan. One of the early pioneers of photography and the art of the photo essay, Annan was commissioned to produced a series of pictures of the centre of Glasgow. From 1868 to 1871 he made at least 31 images that show just how appalling conditions were for so many poor Glaswegians.

Here were tenements built so closely together that, as a paper presented to the House of Commons noted, “the women can either shake hands or scold each other ... from the opposite windows”. The closes were dark and damp, and largely unknown and invisible to the city’s bourgeoisie. Disease was rife, as was every form of skulduggery. Dunghills and dwellings sat side by side and the only time there was running water was when it rained. Nights were especially dangerous and doctors, fearful of being set upon, would often be unable to attend the sick. Mortality rates were higher than anywhere else in Scotland and countless children died before they left infancy.

These were not the kind of places anyone wandered into unprepared. How exactly Annan went about his business nobody knows. But what does seem certain is that in pursuit of his art he was single-minded. As Sara Stevenson, founding curator of photography at the National Galleries of Scotland, writes in Thomas Annan: Photographer of Glasgow, his work is notable for his “vivid enthusiasm”. Combining social commentary with high artistic standards, Annan, a United Presbyterian, knew that what he was documenting was an era in flux. The slums were targeted for demolition and would soon be no more. His photographs were their grim memorial. Published in a book in 1871 they showed Glasgow’s middle classes what was in their midst, and they were shocked. Clearly, something had to be done, and quickly.

Annan’s views of the Saltmarket and High Street portray Glasgow at its lowest point. While others prospered those engulfed in poverty were left to rot – quite literally in many cases. Washing hangs limply from poles, like ragged flags retrieved from the field of a lost battle. Uneven cobblestones lead to labyrinthine closes where only occasionally a shaft of sunlight penetrates. At ground level windows are iron-barred. Men, women and children with nothing to do and nowhere to go stare – just stare – at the camera as if they have no idea what’s going on. They are looking at Annan but, as Stevenson suggests, they are also looking at us, as we are at them 150 years later.

The overwhelming impression is one of hopelessness and decay. There is none of the colour of a Neapolitan backstreet or thrumming chaos of a Mumbai shanty town. There is no movement or energy. In one photograph toddlers, their faces blurred, huddle together. All are barefooted and in need of a wash. They’re not playing nor do they strike a pose, as children would surely do today. We can only suppose that they have no food in their bellies and that they are waiting for something, anything, to turn up and alleviate their plight. History tells us that more often than not that was unlikely to happen. You see the same hollow-eyed look on the skeletal faces of starving people in famine-blighted countries.

Thomas Annan was born in Dairsie, Fife, in 1829, surrounded by fertile fields. In contrast to what he would later witness in Glasgow people were few and far between. The area was known for its production of linen and Annan’s father owned a mill on the River Eden which produced thousands of spindles of thread annually for the trade. In 1845, he was apprenticed as a “Lithographer, Writer and Engraver” to a newspaper proprietor and publisher in nearby Cupar. Four years later he moved to Glasgow where he joined a printing firm and began an association with the city that he would maintain until his death – mysteriously from suicide – in 1887. He married Mary Young Craig , the only daughter of a “victualler”, in 1860 and they had seven sons.

Initially, Annan worked in partnership with George Berwick, a former medical student at the university of St Andrews, who understood how technically to commercialise the photographic process. When the pair went their separate ways, Annan opened his first studio in Sauchiehall Street in 1857. Soon, notes Stevenson, he was employing “one man and a boy” and travelling around Scotland taking striking photographs of notable buildings and the landscape, including Iona, Hamilton Palace and Glasgow Cathedral. In the decades that followed he secured his place in the history of photography, which was already indebted to the distinctive contributions of his fellow Scots, David Octavius Hill and Robert Adamson, who, between 1843 and 1847, marked the first use of photography as an art form.

Annan, however, raised it to a new level. One notable essay, for example, took as its subject the transformation of Loch Katrine into a reservoir which would give Glaswegians access to clean water, which to this day remains the city’s main source of supply.

Acutely aware of the loch’s poetic association through Sir Walter Scott’s The Lady of the Lake, Annan imbued what was an incredible feat of Victorian engineering with mystic beauty. Another of his subjects was Glasgow College, as the university was then known, which had been situated on the High Street since the 15th century. Four hundred years later, the sylvan fields which had for so long surrounded it were covered in slums, and students and staff were continuously disturbed by the “nightly pandemonium of screams and policeman’s rattles”.

As the university authorities prepared to up sticks and move to the newly fashionable west end, Annan photographed the handsome buildings that had stood for centuries and which would soon be demolished to make way for the railway.

It was a critical moment in Glasgow’s history. The flight from east to west of the educated classes was a signal to some that they were abandoning the destitute to their fate. Others, meanwhile, felt that the move was long overdue and that if Glasgow was to flourish it was imperative that its university keep pace with the dynamic spirit of the times. Annan – “the personification of truth, and the soul of honour”, as he was described on his death – seems certainly to have appreciated that what he was photographing was more than just bricks and mortar. Not only would the old university soon be no more but neither would the slums and their sad denizens. It was the end of a chapter in Glasgow’s unfinished story.

Thomas Annan: Photographer of Glasgow by Amanda Maddox and Sara Stevenson is published by Getty Publications, priced £32.50