Thanks.
The consensus of the nearby plotholders is that this is about 60 years old.
It's an odd construction (to me) being made of those laths nailed to uprights.
The floor is rotten underneath those patio decking planks, but the storage crates will be standing on an old door(!) which is in good condition.
I'm supporting the crates by screwing them to sturdy but cheap wood stakes formed into a rough frame.
I'm trying to work out if I can molish a door of sorts for the shelter (which would make it a shed again). I'm considering a 5ft X 6ft sheet that would lift on hinges to make a shelter when open. How to do the hinges is defeating me at the moment.
All good fun (& not expensive fun at that)