I have generally accepted that typical Domestic WiFi has a generally limited range of around 50 Metres.
Because of the failure of my old PC, I have not dome any WiFi checks, such as ACRYLIC or inSSIDer for about 4 months; but tried Acrylic some days back.
I was surprised at the larger quantities showing up; and also of the decided increase of BT WiFi Hotspots, now clearly identified.
Especially as there are no significant quantities of new houses and the BB system has been running for about 3 years.
I decided to try seeing the ranges/distances, using those BT Hotspot sources as generally being similar if not identical sources. ignoring specific locations, orientations etc.
Also there is a BT WiFi Hotspot mapping facility available, so that was likely to give me an independent source of locations.
http://www.btwifi.com/find/uk/index.jsp
----------------------
The results have surprised me.
One BT HotSpot to the WSW is about 164 Metres to its apparent centre, on about the same level; but shadowed by a 90 M, 1970s Steel-Framed, Single Storey Primary School
The faint, furthest one to the ENE is about 320 Metres on the same basis; but it and the remainder are on significantly higher ground, effectively almost overlooking my location.
At present, I can't tie in to the named list from ACRYLIC; but Signal Strengths may yield clues.
I will attempt a more rigorous survey shortly.
Of course, it also is limited to what is "Detectable", not necessarily "Usable" and as I am on EE rather than BT. they are not accessible to me.