The man responsible for English history’s most famous conflagration was sitting on a concrete wall and holding up two burnt pies. He wore a baker’s white hat and had soot smudges on his cheeks. “Higher,” said the photographer, and Thomas Farriner – for it was he – lifted his pies to London skies. I came across this impersonator of the bungling baker whilst paying my own homage to the Great Fire of London, which started in Farriner’s shop 350 years ago this summer.

The precise date was September 2 1666 and the Museum of London is marking the anniversary with a major exhibition, entitled Fire! Fire!, which opens today . It’s a cleverly judged show with plenty of atmosphere and interactive elements for children (the fire features prominently in the national curriculum) as well as more meaty scholarship in the form of original letters, maps and poignant artefacts such as pitifully tiny leather fire buckets and someone’s charred Bible.

Pudding Lane, the site of Thomas Farriner's bakery, 202 feet from Monument Credit: Getty

The museum is also offering guided walks through the streets consumed by the flames and I was enjoying a special preview walk, guided by the curator of the exhibition, Meriel Jeater, when we encountered the Farriner lookalike in Pudding Lane. We had started the walk at the Monument, the classic Doric column designed by Wren and built in the 1670s to commemorate the fire that, according to the inscription on its base, “…rushed devastating through every quarter with astonishing swiftness and noise…” (though, officially at least, it claimed just a handful of human lives).

The height of the Monument (202ft) and its location are such that if you were to topple it in an easterly direction, and burly giants in hard hats were to lower it gently to the ground, its top would come to rest on the site of Farriner’s bakery, now an expanse of tarmac where Pudding Lane meets Monument Street. The exhibition re-creates Pudding Lane as a sort of three-dimensional 17th-century woodcut, complete with original hanging shop signs, while an audio-visual display illustrates the moment when the fire sparked into life in the early hours of Sunday September 2 1666.

At the site itself, Jeater set the scene: “There was a storm blowing from the east. London was really dry because there’d been a drought. Pudding Lane was full of warehouses with combustible things so the fire had a strong foothold from the beginning and the weather conditions just exacerbated it.”

During late 20th-century excavations some of those “combustible things” were found in a basement within a few yards of the bakery – 20 barrels of carbonised tar that must have gone up like a bomb. Though people tend to think the fire destroyed everything in its path (including 89 churches) it also created its own time capsules.

Throughout the city, debris from the fire formed a layer that sealed in medieval cellars and their contents and it’s only in the last few decades that some of these have been discovered (one, for example, being under what is now the New Look store in Gracechurch Street). Many of the retrieved objects – burned bricks, singed floor tiles, iron padlocks, the stems of goblets, clumps of hooks-and-eyes that have melted together – feature in the exhibition, forming a powerful testament to the effects of the blaze.

A map showing the extent of the fire's damage

Strictly speaking, it was never a single blaze but a Hydra, licking through the old lanes in all directions. On our walk, Jeater and I followed the progress of one of the fire-waves as it rolled north and east. The City was rebuilt post-fire, brick and stone replacing timber, but the medieval street pattern is still in place. The warren of lanes between Lombard Street and Cornhill are especially redolent of the pre-Great Fire days.

London’s first coffee shop was tucked in here and the diarist Samuel Pepys – whose vivid eyewitness accounts of the fire (the panicking pigeons, the singed cat) form a leitmotif of the exhibition – records visiting it in 1660. Six years later the café was burned out as flames surged up into Cornhill and engulfed the Royal Exchange.

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By Tuesday the flames had spread along Fleet Street to Temple. At 8 o’clock in the evening fire broke out on the roof of St Paul’s Cathedral, which was covered in wooden scaffolding, and the roof collapsed into the cathedral. Down among the monuments the alabaster tomb and effigy of one William Hewett, merchant, was badly damaged by the flames. What remains, his charred head and shoulders, is on display in the exhibition along with carved stonework from old St Paul’s.

Meriel Jeater and I finished our walk near the Museum of London. Here, London Wall, a postwar freeway, crosses the site of the church of St Olave and in a small park to the south an ancient, weathered stone tablet, bearing a skull and crossbones, records that St Olave’s was “destroyed by the dreadful fire in the year 1666”. It was one of the last churches to burn.

“Around midnight on Tuesday the wind dies down and on Wednesday people get to grips with the fire,” said Jeater. “By dawn on Thursday it’s smouldering. Then you’re left with this ruined city full of thieves and cut-throats.”

Thieves and cut-throats in the City of London? Perish the thought.

Essentials

The Museum of London (020 7001 9844; museumoflondon.org.uk) at 150 London Wall is open daily, 10am-6pm. Fire! Fire! runs until April 17 2017: admission, adults £8, children £4. The museum offers a 45-minute talk for groups by the curator of the exhibition (£10pp), a Great Fire walking tour of the city (90 mins to two hours at £20pp), as well as shorter walks for families and storytelling sessions during summer school holidays.