Gloucester gutters, specifically
What actually blocks Gloucester gutters.
Gloucester sits low in the Severn Vale, and the city knows what heavy rain does. In the July 2007 floods a lot of the damage across the county came from surface water, where rain simply fell faster than drains could carry it away. No gutter stops a flood like that, but plenty of everyday water damage in the city is smaller and avoidable: a part-blocked gutter overflowing in a summer downpour, water running down the brickwork behind a blocked downpipe, and a damp patch appearing inside months later.
On the estates, the main culprit is moss. The concrete-tile roofs across Abbeydale, Abbeymead, Matson, Tuffley and Quedgeley grow a lot of it in this damp air, and every heavy shower washes clumps off the tiles and into the gutter, where it settles into a thick, silty layer and slowly closes up the outlets. That's why a roof clean and a gutter clear go together, and why the gutter clear is free when we do the roof.
Nearer Robinswood Hill, Gloucester Park and Alney Island, and in older suburbs with mature gardens such as Hucclecote and Barnwood, it's leaves as much as moss. Those are the houses where once a year often isn't enough.