To clear things up.
When you first load Google Maps the locate me is based on your current cell.
Your phone tells google "Hi I'm on 234-12345" and Google then has a look in it's massive database and goes, "Oh, people who use that cell tend to be located around 52 deg 48' 40.30" N, 1 deg 13' 55.33" E, but with a margin of error of about 1 mile"
Your phone then puts a blue dot at the spot and places the blue circle a mile around your location.
Google does not use multiple cells to trianglate your location, they just use the one cell.
Then when you enable the GPS (via the menu), your phone tells Google Maps "actually I'm at 52 deg 48' 40.50" N, 1 deg 13' 54.78" E", this then removes the blue circle and moves the blue dot to the correct location.
What also happens is that your phone tells Google "BTW I'm on cell 234-12345 and my location is 52 deg 48' 40.50" N, 1 deg 13' 54.78" E". Google then decide with all this data (plus all the others on the same cell) whether they need to move or adjust their original statement for those without GPS.