Wikipedia explains all.
Complicated, isn't it? Note that the Hampshire map has less wiggles than Traveline's. The W2 runs every hour until late at night BUT ONLY ON SATURDAYS.
... you can find these two. But, as usual with on-line stuff, it is easier if you know what to look for in the first place. Likewise, Traveline reveals all if a "Location" search is chosen.
This list implies that the W2 is either "new" as per Mr Hammond's letter; or has recently changed, whilst First thinks it has been running since April 2016.
We will conclude tomorrow and contrast with publicity for another out-of-town shopping centre that we have "visited" recently.