Not a shed, a basement.
The highlights included most of a car down there, seats, body panels, wheels, etc. and a steel box (I still have the box) containing 70s/80s porn.
Is that you Shaun?
Mate of mine (called Shaun obvs.) found very similar, bought a big 3 storey end terrace (late 19thC build) for bugger all as a project.
Found that one of the walls of the cupboard under the stairs was actually a door that had been nailed shut, probably some time in the 60’s and filled/painted. House had changed hands many times between then and when he got it (late 90s). It’d been a family home, student digs, a drug den of sorts and empty for several years too. No one who they could track down knew anything about it.
The basement windows and exterior door had been bricked up and covered from the outside (either flag stones, flower beds or weeds all round the house!), there was still working heat, electricity and water down there. Also an almost complete Series II Land Rover, mostly restored and ready to rebuild, two classic motorbikes plus loads of parts, thousands of pounds worth of old tools and workshop supplies, stacks of high quality wood ready for whatever projects the person who bricked it up had in mind. A mini lathe, pillar drill and a few workshop style woodworking tools. Dozens of old workshop type books cars/metalworking/woodworking/electrical/plumbing/bricklaying/roofing all sorts.
And about 200 kilos of dust.
When i moved away from the area a couple of years after they moved in, they were still trying to sort out the basement, while simultaneously trying to make the house habitable…