Went to Mersea Island on Saturday and, using OSM on my Garmin, was surprised to find there was nothing mapped but the coastline. Not even the roads leading to it. Was able to fill in quite a few roads including the causeway onto the island and a couple of footpaths, and have use the aerial images to mark out a few bits of land use, Cudmore park and the village of West Mersea. I also used the aerial images to move the coastline in a few places where it was clearly wrong otherwise the roads and paths I was on would have been underwater!