WM,
We need a GR9 chap to comment but my understanding is that the GR9s are coming out of Afgh purely to service CAS's whim to get GR4 (or Typhoon) in. The comment in the various bits of media (and the excellent book by Cdr Orchard) is that the GR9 could happily carry on in theatre and, with a bit of juggling, do quite a lot of the sea bit as well......but I am definitely no expert here. Indeed it would save Defence the (about) £500M it is costing to get GR4 in (including wet concrete) - whose hair-brained idea was that.....oh yes Leeson/Andersons.
