All the areas that have been 4G'd near me were never scheduled to be given 4G, it just appeared one day randomly. Nothing on their coverage checker, even their social media team had no idea it went live. Got only knows why they randomly decided to 4G it. There are still two legacy orange sites live which cover the valley and both are due to be MBNL'd in the next three months.
Hopefully Three will pull their finger out of their arse and start rolling out a bit more aggressively, they have their work cut out trying to catch up to EE. That said, all of the networks have a long way to go to catch up to EE. VO2 have already started upgrading loads of sites near me, they have 4 masts covering the valley compared to 2 for Three. Should they upgrade all four then they'd almost certainly have blanket 4G coverage down the valley.