Not quite obsolete, but nearly. -
Unusually, this is in the :loser: repository, in :loser:/fixedpoints/scripts/convert_shx/
We think this turns a shapefile which holds the coordinates of the 1623, 1624 boundaries into GPX. But we have mislaid the shapefile containing this vital data.
It runs ogr2ogr -f csv -lco GEOMETRY=AS_WKT outputfile inputfile and then extensively post-processes the shapefile output.