The electrical engineer pulled what he believed to be scrap iron or a gas canister from the water on Monday and took it home intending to recycle it - only to realise that he was actually in possession of a World War One artillery shell once he had cleaned it and Googled pictures of the ordnance.
Mr Briscombe's family home in Knaresborough and two entire streets had to be cleared while police and an army bomb disposal team dealt with the shell - believed to be a battlefield souvenir brought back from the trenches - and detonated it in a controlled explosion in a nearby field.
The A59 had to be shut for two hours during the operation and 30 houses were evacuated.
"I was doing a litter pick near The Watermill cafe, which my partner owns, as we like to keep the area looking nice. I found what I thought was a gas canister, so I put it in a bucket intending to separate and recycle it when I got home. I hosed all the gunk off and realised it wasn't scrap metal! As soon as I looked it up online I called the police," said Mr Briscombe.
"Had I known what it was, I would never have disturbed it. It just looked like a mucky lump of iron."
Mr Briscombe covered the object in sandbags while he waited for military experts to arrive.
"It's pure speculation, but the disposal team thought it was a war trophy that someone had brought back home from the battlefields. Perhaps they died and their house was cleared and someone couldn't be bothered to dispose of it properly and threw it off the bridge. It's amazing what people throw in the river - last week I found a sewing machine dated 1896.
"I didn't just take the bomb home for the fun of it! I'll look a damn sight more closely at what I take out of the river now - and I might give the litter picking a rest for a week or so."
North Yorkshire Police advice
If you come across something that you think may be an explosive device such as a bomb, shell, mortar or marine flare for example:-
- Do not touch it
- Leave the item where it is - even if it looks old and rusty, it may still contain explosives and is therefore potentially dangerous
- Move at least 50m away and call the police on 101 and give them clear information about the location of the suspect item.
- If you don't know the postal address, provide the police with details of local landmarks.
- If you are able to you could provide a description of the item, including any markings that may be on it.
- The police will make contact with the Explosives Ordnance Disposal Officer (bomb disposal officer), who will be able to take the necessary action.