Thanks Andrew for your comments. I agree the OSM descriptions for "footway" and "path" do not make it clear cut which one to use. In truth the Coastal Walk is a mix of different types of construction - some parts fairly natural, some stone paving and some raised boardwalks. I think the "surface=metal" (which I did not use) is from an older generation of this path, which is now gone. I had not appreciated that OSM had not been updated with the re-alignment until after my visit - so I did not record or map where the boardwalk sections are .