From what I can remember of that product, and of RAF Wittering Itself, that seems about right.
Because Wittering Operates the Harrier, it lands vertically on a concrete pad, (or it did when I was there for a day or two), so it probably doesn't need taxiways.
But a few years back (well perhaps decades), there were a load of USAF ANG A-7 there. Can't believe thay were taxying on the grass. Or have they dug up the concrete?
And Google Earth version of Wittering looks like this:
It begs the question 'Which came first.. the Harrier or the Airfield' There is no good reason the MOD would dig the taxiways up as to do so would cost them money. Also.. I'd have thought it unlikely that Harriers always land vertically. I've got the Sigma Harrier so will have a look at Wittering (though it's likely I didn't install the scenery that came with it)
RAF Wittering has been an airfield for a looooooooong time, the airfield was extensively updated when the V-bombers were being introduced during the early 60s. In the 80s our Sqn deployed 6 aircraft on a regular basis; the whole airfield was updated, wider taxi ways, large radius turns and QRA ORPS on the eastern approach. Also the Harrier normally lands with a roll, as vertical landing uses a lot of fuel and cause enormous stress to the airframe.