Alistair Gunn wrote:

In sci.military.naval Guy Alcala twisted the electrons to say:
The GR.9s can stay on station far longer than the SHARs could, and AEW
cover allows them to orbit at altitude instead of down low, increasing
their endurance even more.

I think I've become slightly confused wrt the Harriers versions. Is the
following correct?

GR7 + systems upgrade = GR9
GR7 + engine upgrade = GR7A
GR7 + both upgrades = GR9A

Yes.

In which case, does this mean there will still be "ordinary" GR7s around
the place, at the end of this? (ie: Are we effectly back to "fleet of
fleets" again?)

Not as I understand things. Try here (although the explanation seems about
as clear to me as John Cleese's master explaining which hook to hang your
coat on in "The Meaning of Life"):

http://www.harrier.org.uk/technical/Harrier_GR9.htm

I don't know if that's the most current thinking.

Guy