It's possible this hyacinth started life inside. I always find the smell intolerable over time, it has a bright airy horror that reminds me of slug egg cases and other people's plastic toys. We used to force a hyacinth or four in our airing cupboard in the deep winter months when I was a child, and everything was trapped indoors, including us, and the smell of them has never quite lost the association. Perhaps someone, seduced by the bright colour, took it home, only to find the smell cloying in a small dark damp Oxford basement flat, and out it went, into the moss yard.
That buddleia and the harts tongue fern look as self-sown as the moss, and the cheerful pot of primulas is (like the hyacinth) just visible from the garden, a little spring sun in the lightwell. The old stump is presumably the buddleia's old dad, still hanging out in with the kids, mossing over in the corner.