Presumably, however, there is some geographical information that is open
and could
be published, e.g. courser geographical information based on just the
postcode district.
http://www.mysociety.org/ claims it publishes geo locations for NI
postcodes: http://parlvid.mysociety.org:81/os/ONSPD_FEB_2012_UK_O.zip
and apparently it got them from here:
http://www.ons.gov.uk/ons/guide-method/geography/products/postcode-directories/-nspp-/index.html
which says that they are licenced on Open Government Licence terms.
I see BT (i.e. Northern Ireland) addresses in there, so it seems that at
least you can generate URIs using the same scheme, even if the
dereferenced data is of lower quality (it may not be, I haven't looked).
Steven Pemberton