Geocoding not working with Isle of Man

Geocoding doesn't seem to work for addresses within the Isle of Man. As far as I can see this is because Google doesn't treat the Isle of Man as a separate country, so it isn't returned in the list of countries that Google supports geocoding.

I've tried simply removing the location.im.inc file, and treating the Isle of Man address as a UK address, but this doesn't seem to work. As far as I can tell the request to geocode still doesn't get sent off. I've also tried taking the UK geocoding hooks and adding them to location.im.inc, and still no joy (I think that's because Google doesn't treat it as a country, as mentioned above).

Is there some other location that contains a list of valid geocoding locations that I'm missing? I've flushed all the various caches, and have tried truncating the zipcodes table as well, but still no joy.

(I've had to also use a web archive version of the XML that contains the valid geocoding countries, since that XML file seems to be down at the moment, but the actual geocoding problem was occurring before this happened.)