Who or what stays in here?

Went to visit my in-laws today who stay in Fyvie Aberdeenshire. Granda is almost 85 but his garden is just imaculate. When they moved into their house 20 years ago he built this hut out of large concrete slabs and a cotoneaster grew up the side. He started trimming it regularly and over the years this is the result. In the summer it is covered with tiny white flowers. Whats inside -- you've probably guessed, yes its his wheelie bin.