Large amounts of bird droppings on pavement, cars, walls

We have a chronic issue with large amounts of bird poo outside our block of flats (Lashio House, Clissold Crescent). Many children live and play in the area and it is a constant worry. It is often impossible to walk around or push a buggy around, causing contamination. Ideally it would be fixed at source but the Hackney tree officer refuses to do anything. This is our only recourse, to ask for cleaning. Any help very much appreciated.