In reply to pebbles:
Your right I had forgotten that they haven't finished the integrating/consolidation of Orange sites into the EE network (which originally was a share between T-Mobile and Three).
However the shift in coverage isn't due to 4G; both articles are wrong in this respect.
When Orange and T-Mobile merged to become EE (before any 4G was deployed or even planned) they announced they would rationalise the two separate site footprints of c.13,000 orange sites and c.16,000 EE sites into a single rid of 18,000 - 20,000 sites; this process is nearing completion now.
Overall the amount of 3G coverage increases but there are winners and loses in the process (the same will happen as Vodafone and O2 consolidate their two separate portfolios down to c.18,500 shared locations ~ though in the process the number of 3G locations each operate has will increase from c. 10,000 to 18,500).
EE deployment of 4G is hapenning across the consolidated sites (e.g. 18,000 - 20,000) and does not affect the 3G network as its a different frequency and different base station equipment.