Fluffy,If you look carefully you'd find that the GCS is not being fitted with Phalanx 20mm. Instead it is a Phalanx-based directed-energy system. This seems to explain the hangar-mounted system: Firing cased-ammunition over the flight-deck is considered by many a no-no....
[ Will try to find a link to Think Defence blog.... ]
WHAT have you been smoking ?????
Any of the BAE press releases I've seen (or that I've found on the BAE site & posted within the annals of this thread), as well as those released through other 'defence information websites' have never mentioned directed energy weapons.
http://www.baesystems.com/slideshow/BAES_027169/global-combat-ship
I would say it's Phalanx, or the LADS based on the phalanx mount (as mentioned in a previous post or two).
SA