Weapons.

This is coolbert:

Originally I thought this might be a weapons cache from the era of the Cold War as placed there by Soviet spetsnaz. Or maybe a Gladio stay-behind mission.

But evidently the thought is that this is IRA. Irish Republican Army.

"Teenage metal detector trawling Somerset river stumbles across hidden cache of 40 'IRA' weapons - including 'Widow Maker' rifle and Nazi machine gun"

 *   "James Cork stumbled across cache of weapons"
 *  "The 16-year-old was trawling the water with a magnet"
 *   "Experts say some of the . . . may have belonged to the IRA"
 *   "Among them . . . a Nazi MG 42 and an M16 assault rifle"
 *   "IRA hid guns and explosives all over the UK mainland"

Terrorists acquire weapons, then store same for future use. Store in a manner where they cannot be found [by ordinary methods] and must be coated with some sort of preservative so they will not deteriorate.

This does seem to be an weapons cache of the IRA. An odd conglomeration of weapons and not standard issue as might be the case for Soviet spetsnaz.

That Easter Accord that ended the "Time of Troubles" in Northern Ireland specified the IRA had to eliminate their weapons arsenal.

Eliminate not so properly defined but rather considered as inoperable or out-of-reach.

Weapons as found at Somerset merely dumped from a bridge into the water and left. "Inoperable and out-of-reach" by any standard?

coolbert.