PPPS (and this one's pedantry, I admit): There's no such thing as a "WAH-64D". It's a "WAH-64".
Not according to the MoD factsheet, and not according to Jane's.
...allows us to operate the aircraft at full operational capabilities, where the rest of the AH-64 users cannot
Used to be true, but not so anymore. Improvements to their engines and transmissions means the US Army machines now have about the same power output as the UK aircraft.
...the AAC to operate effectively from ships....which the rest of the AH-64 users can't.
Dutch Apaches are 'marinised' also.
however most of the modifications to the AH-64D to the new E standard
are to allow the US Army to have an Apache as good as ours.
You're so so wrong. The AH-64E (Block III) will be light years ahead of the WAH-64D (Block 1-standard) Apaches we currently operate in any differentiator you wish to choose.