There’s gold in the hills of Scotland, and it is the rarest and most valuable gold in the world. Scottish gold was used in the crowns of James V and his queen in the 16th century, but these days anyone planning to get rich quick is going to be disappointed. The gold is in tiny flecks that have to be panned from rivers with great patience — although the occasional rare nugget of gold does turn up.

The gold comes from veins of hard rock, worn down over thousands of years by rain, frost and sun. Once the gold is liberated it gets washed away in rivers, where goldpanners sift through the sediment searching for the dust-sized bits of gold.

The right amount of rainfall is particularly important — too little decreases the river flow and the gold gets buried rather than flushed out, but heavy rainfall leaves the rivers flowing too high and fast to work safely. This spring the rainfall and river flows have not been great.

However, the dream of all goldpanners is a seriously big flood, perhaps a once-in-a-century event on the scale of the 2004 Boscastle flashflood in Cornwall, when a river turns into a raging torrent.

“Really heavy rain can send a whole riverbed into motion, crushing and freeing the gold,” explains Vince Thurkettle, champion goldpanner and Britain’s only full-time gold prospector. But even after such a rare flood, this is hardly the stuff of a Klondike gold rush.