I think the reasoning is that supposedly Virgin is already here but in actuallity it covers a tiny portion of Washington. Here there was originally Washington Cable but they went bust and Virgin came in after going through Sunderland. However they only ended up covering a tiny portion of Washington but we are still in a 'virgin covered area'
Anyone looking at this map
would be able to tell you that Washington is crying out for better broadband. There is more than half of the town, about 10 thousand homes, syncing at less than 1-2 mb. I am lucky if at 3 am when very few people are on the network if I can get to 90kbs, more often than not it is in the 50s. The jump to fibre is going to be a day one purchase for a lot of people. So the one area live already is one of the only areas that was already getting 30+ from Virgin.
But these higher speeds have skewed the averages for everyone else delaying any roll out in the past.