A Metallic Mystery

Found on Marloes Sands, November 1st…
So how did it get there? Steel bolts and two very heavy galvanised steel brackets – certainly didn’t float in!
And I doubt it has been through a fire, because of the state of the zinc plating.
My suspicion is that some part of a heavily engineered wooden frame got washed in, and the surf was so rough on the shore (the sea has been VERY rowdy recently) that all the timbers got smashed away.