The largest gold nugget found in British waters for 500 years has been discovered by a man lying face down in a river in Scotland.

The man, who wishes to remain anonymous, came across the 85.7g (2.75 Troy ounces) lump with a method called 'sniping', in which the prospector uses a snorkel to lie face down in the water and search the riverbed. Named the Douglas Nugget, it is expected to be worth at least £50,000.

The discovery was made two years ago but its precise location remains a secret to avoid Scotland's biggest gold rush in years. Upon finding the nugget the man - in his 40s - ran from the water clutching his gold shouting “bingo”.

Finally breaking his silence, he said: “I was following a crack in the bedrock and found around 2g in fine gold.

“This then led to a pocket, where I uncovered the nugget. I called over my friend to have a look and we both assumed it to be around 5-7g in weight.

“It wasn't until I removed it that we realised just how big it was.”

He added: “I took off my glove and picked it up, jumped out of the water and screamed, 'Bingo!' to my friend.