1. Zoom in, select polygon tool(), draw around house.
4. Save the edits to server
5. Select/hover over your shape on the map
6. Download as GML
Note: Downloaded data is derived from Ordnance Survey.
Please see the OpenSpace Developer Agreement.
In short: they own it, but you get a "perpetual non-exclusive" licence for use in other non-commerical works.
), draw around house.