Hi All
I've mapped the changes to Three's planned 4G coverage for "end of 2015".
https://www.google.com/maps/d/viewer?mid=zOAnXJFLQHC...
As you can see there are lots of places that will get reduced coverage. It seems that Three plan to fill in some gaps in their existing coverage without expanding out to more remote areas like Kent...
All info came from Three's own coverage plan page http://www.three.co.uk/Discover/When_will_I_get_4G