Update, 15 November 2011: I have been notified by TeleAtlas, who provide the mapping data for SatNavs etc., that they have updated their information for our location. Hopefully this means that your SatNav will soon be capable of bringing you to our gate rather than some random slate quarry. How long it will take Google to update their information is another matter: they still think that our lane, and the farm track up to the house, is called "Beeches Park" for some reason. Google Streetview also shows this route disappearing into the hedges at various points, which is not recommended.
We've recently noticed that a number of apparently unnamed roads in North Wales and Anglesey have been given completely random english names by Google, which doesn't exactly help with route-finding. Do they have a street name generator tool that comes into play whenever they have a problem? Or is it just a bored data entry technician exercising a bit of desperate creativity? We may never know.
[Google: "Great just isn't good enough".]
The council have now installed our new street name plate, and very fine it looks too.

So our "official" address is now:
Cae Mawr B&B
Lôn Tyddyn Agnes
Llanllyfni
Gwynedd
LL54 6RT
However, it may be a little while before SatNav starts working properly. So please look carefully at our directions page on the website when visiting, or you may still find yourself in a quarry!
(As those of you who have been watching Snowdonia 1890 will know, a "tyddyn" was a smallholding. Tyddyn Agnes was just a little way up the lane, but has not really existed as a smallholding for many years.)