She doesn't appear to be within 3 miles of anyone who uses an ad-blocker, Factor30! (I've not got any ads on this page, but don't tell the Ed!)
Advertisers can get a rough idea of your location via two ways. Firstly, they can look at your IP address. However that is often unreliable at a level below seeing which country someone is in. For example, I'm currently seen as being in Twickenham (when I'm actually in Suffolk!). Click here to see where the system thinks you are:
http://whatismyipaddress.com/
More accurately, your browsing habits can be tracked, to see which sites you visit and which searches you make. So, for example, if you search Google for restaurants in Manchester you're likely to see Manchester-based ads when you come to AB. (With Firefox you can tell websites that you don't want to be tracked. Other browsers probably offer something similar).