Keen to make his own, Warshawsky took the unusual step of fashioning a Heath Robinson-style charcoal furnace. He built it in the garden of the house he shared with James Ross-Harris and Richard Warner in south London hipster hotspot, Peckham. All three got the forging bug, and their weekends were spent in trial and error. “It’s not something you can pick up straight away,” says Warner, with some understatement. A year later, their hobby had become an obsession. In that time, they’d transformed materials they’d picked up skip-dipping into a roasting-spit, a hot tub and a distillery.

In 2013, they turned that obsession into a business, setting up Blenheim Forge. Their skills are on show the minute visitors turn into the row of railway arches, in the form of a big rusty gate welded together from a concoction of metal odds and ends. Inside, the dark, oily space is more gritty Dickensian workshop than chic 21st-century studio. Here, they painstakingly produce kitchen blades to rival the Japanese masters.

Making such beautiful, high-performance knives by hand is a laborious business: hot-forging and cold-forging the blade, hammering, welding, sanding, polishing, etching, sharpening... and so it goes on.

“At the beginning, we were not making knives quickly enough…it would take us around a couple of weeks to make a single knife”

While they clearly love getting involved with every aspect of knife-making, much of their effort, time and money has been invested in tools and machinery to make their processes more financially viable. For this they drew on their education and professional backgrounds. Warner and Ross-Harris studied design and engineering at Goldsmiths and Queen Mary University of London. Then Ross-Harris had worked as a blacksmith for three years, while Warner had spent short stints working for a joiner, and at the research and development department at Dyson. Philosopy graduate, Warshawsky, had been dabbling in carpentry. They also took inspiration from videos of Japanese knife-making factories.

“We sold a few in local markets, but at the beginning, we were not making knives quickly enough,” admits Warner, who can’t shake hands on the morning Furnace visits, as his are already smothered in oil.

Warshawsky agrees that “it would take us around a couple of weeks to make a single knife when we started out.”

So the trio set about amassing the tools that would help them quicken their pace. Some they bought, such as the forging equipment. Others, like their first bespoke belt sander, they built themselves, “because you can’t buy some of the stuff we use”, Warner explains.

Now they have a suite of tools, some of which “can take ten minutes off the making of each knife”, adds Warner.He points a greasy finger to the grinders with their custom-made, water-fed abrasive wheels that are common in Japanese knife-making factories. These have really speeded up the process, because the trio no longer have to keep dipping the knife in water to cool it down.

And since early 2017, Blenheim Forge’s actual forging has taken place out of town – to appease neighbours who had complained about the noise. Now, two of the team head down to a barn on a farm in Petersfield for two days a week “to do the hot work”, as Warner puts it.

Through these efforts, they can now make 10 knives in two days, a significant improvement on the early days. And although the protracted process is part of what makes their range so sought after, it also explains why orders take three weeks to complete.

Blenheim Forge uses springy Swedish steel for their £350 Damascus knives and premium Japanese Blue Paper carbon steel for the others, which start at £140 for the Petty. At the moment, all the steel is pre-laminated, but they aim to improve their knives even further by making more of their own steel and laminating it themselves. For this they have a 100-year-old rolling mill, which will allow them to make good laminates in significant quantities.

While Blenheim Forge is no slick production line, it’s the hands-on process that the founders are perfecting. Which means their knives will become ever-more covetable.

And, as random as knife-making might seem, it actually fits well into a host of other artisanal trades enjoying a renaissance among the urban young. These are typified by the three B’s: bakery, butchery and barbering, all of which would benefit from a sharp blade.