The common was the land between Gambledown Lane, The Banks and Chapel Lane.

The Mottisfont Estate Path 6-mile circular footpath relation (osm.org/way/2161924) has a gap to the south of here. I think because it was re-rerouted to avoid the Abbey car park.

is this actually a pond? nothing on satellite or OS opendata. could be intermittent

Renamed - 'Centenary Border Pavilion'

Could you check this road, there is feedback from the driver, which shows that he could not drive. Maybe is there some kind of obstacle, access ban, gate or something else?

Kings Chase development actively progressing through 2019, but not all areas currently accessible and mostly not yet visible on aerial imagery (ESRI is most up to date as of today). Still needs full survey, including road layout and naming.

From OpenStreetBugs:
Description: missing footpath about here, leading from the A3057 to the footpath to the east. a bit difficult to survey though as there are no easy onward connections at the A3057 end, necessitating walking along a busy A road. Rather you than me :-) [nickw]

South of this point, it's a path not a track

It's a path, not a track, between here and where the track from near Rangebourne Cottage joins