Re Nimwacs - when the various options were shown to 8 Squadron S**gs the elements of disbelief were quite interesting:
Option 1 - A bastardised Andover (just being withdrawn from service so plenty of airframes) with bigger wings, extra jet under each wing (think Shack MR3) and tons of extra fuel - and requiring an 11000ft runway!!!!
Option 2 - An updated Hawkeye. The Gannet guys loved the idea but would probably have needed a carrier to go anywhere
Option 3 - Nimrod with the radar developed for (but never flown) a Blackburn design to go on the new RN super carrier (which had been cancelled). On the face of it a good idea but unproven
Option 4 - E3
Needless to say the Sqn (almost to a man) said go for E3, but the decisions were being taken by the OR lot at MoD, which (if I remember) didn't have any AEW guys in it at the time, or if they did he was too far down the pecking order to have any real input.
I was only surprised we didn't get the Andover variant!
It was a shame they ended up destroying so many good Nimrod airframes which would have been available much sooner (and with fewer hours) for MR4A.