In message , at 16:23:16 on
Wed, 12 Feb 2014, Graham Harrison
remarked:
Finally, I assume that the "current location" only works if you are on
public Wi-Fi or 3G and not on fixed line BB.

If you are using private wifi (with a broadcast, and hence public, SSID)
it could know too. In fact I think all it normally takes is for your
laptop to have its wifi switched on, and be able to "see" some SSIDs,
even if the connectivity being used is BB.

Yes, it works from my iPad, but not from my cable-connected PC (both
using the same wireless router).

I wonder if it's linked to GPS in devices like a mobile phone/iPad?

If it's switched on, yes. We were examining the situation where it
isn't.

When I use my desktop which is wired to my BT broadband various
websites that try and guess my position seem to think I'm almost
anywhere between Somerset and London; it varies day to day.

Is it ever 'right' (ie within a couple of hundred yards).

It's possible they are using IP-address based geolocation, which
basically doesn't work at all given the UK's Internet characteristics
[Broadband users are almost always 'registered' to some sort of NOC up
to hundreds of miles away. Sometimes the details won't have been updated
after corporate takeovers, and some small ISPs deliberately obfuscate
the information leading to variable results].
--
Roland Perry