As part of moving all our GIS data over to clear GeoJSON, I've implemented @type="GeoJSON" for the
<location> element, and I've fixed the five outstanding MultiPolygon problem locations by re-capturing that data from the original KML files from Locating London's Past, converting them to GeoJSON, which results in well-formed GeoJSON geometries. Where such geometries exist in location files, they are used in preference to converting the existing GIS coord lists when building the GeoJSON version of the Gazetteer. There will probably be some fallout in terms of rendering the Google Maps for the short term, but that will be fixable when we move to OpenStreetMaps. For the moment, we're in limbo between two systems.
At the same time, having rebuilt the schema, I found that @precision has been removed from the
<floruit> elements, making some of our code invalid. This is only in the dev version. I've reconfigured my own schema-building process so that it's pointing at the current release version; meanwhile I've reopened the ticket that caused the problem because it does need a deprecation period anyway.