It is a new heli pad for the Coastguard.
Here is my latest guess (and it is just a guess)
New coastguarg heli centre opens. Owners scare away all but the police by building on them.
Police use one Islander.
One Islander does not justify the expense of one runway.
Therefore the Islander gets retired.
And the Police buy a Helicopter (name another police force that uses fixed wing, there may be one or two but therea re not many)
Hey presto, one airfield up for development and it has had the bombs removed.
Fareham and Gosport get building land they 'need' and someone makes a bunch of money.
I give it five years.