Farnborough North seems down a lot. However the figures there are inaccurate- most tickets are sold as "Farnborough Stations" so would be lumped in with SWT▸ 's Farnborough Main.
Not necessarily. At the very least they should pick up
TVM▸ sales from Farnborough North, because the ticketing systems will know the real location rather than what is printed. But they will know a much more accurate figure for sales at Farnborough Main, and they can use this to work out Farnborough North. especially as it is a simple two station fares group.
They explain how they deal with this on pp 25/26 of the report (via the linked page above). Basically they use the ratio of tickets actually sold
from the individual stations as a proxy for those fares sold
to the group of stations from elsewhere. This process has changed over the last few years, and although there was a period when all sales were associated with the named group station, that is not the case currently.
Paul