For the duration of recorded history, gold has driven men to madness. It has driven them to distraction and rage and war. More recently, it has driven people to spend rainy days knee-deep in Scottish streams, sifting through bucket after bucket of wet grey gravel.

Panning for gold, despite its obvious potential upside, could give the appearance of being a miserable and sodden slog. In July, though, it emerged that a gold nugget of 85.7g (2.75 Troy ounces), worth at least £50,000, had been found in an undisclosed Scottish river. It was the largest gold nugget found in British waters for half a ­century, and, naturally, it provoked renewed interest in gold panning. Established enthusiasts found their phones ringing constantly. Orders of gold panning equipment surged. Classes were suddenly booked up, and that was before another nugget, this time containing gold worth approximately £2 million, was unearthed in Western Australia.

I’ve enrolled in one of these classes. It’s a drizzly Saturday lunchtime in the Lowther Hills, where Mennock Burn – one of Scotland’s most famous gold-panning streams – is, for once, dotted with people. Fourteen of us have come to learn how to pan for gold, all clad in waders, knee-deep in the clear, rushing water. We’re led by Leon Kirk and Alan Souter. Kirk, who aside from ­holding classes, runs a business selling gold panning equipment, is a friend of the mystery prospector and was the first to value the nugget. Souter, a retired teacher, is a veteran panner and a geology expert. “You’ll definitely find some gold today,” Kirk told us. There’s gold in them thar rills! And we’ll know when we’ve found it: “Gold, once you see it, has a particular lustre,” says Souter, piratically.