CaMoron and his bean counters scrapped the Nimrods for this role and much more and had them cut up out of spite, just as they were entering service after years of problems and cost overruns, so several billion were written off. Then surprise, surprise, we need their capabilities, so we spend even more money on the inferior (older and not as capable electronic suite) where they are an invaluable asset which any modern military force must have.
It is this sort of political interference and stupidity, that makes our defence procurement budget such bad value. The money wasted here would have paid for 2 of the 6 planned but cancelled type 45 destroyers, which is why the RN is down to 23 major warships.

At some point we are going to also have an AWACS crisis as they are using up their airframe flying hours life much faster than was anticipated due to Iraq and Afghanistan and other areas of concern.
Didn't read the Wikipedia article then Rods

Commercially, the 707 is the reason why the RAF got Comets as the basis of the Nimrod in the first place. BOAC couldn't give them away, same applies to the VC10. Neither had the range, speed or reliability of the 707 airframe, it taking years and millions of pounds of military development to make them very good at what they did.
http://www.spyflight.co.uk/nim%20aew.htmSeveral very informative reasons why the latest Nimrod got binned...
http://www.arrse.co.uk/community/threads/nimrod-mr4-was-not-airworthy.157017/The same applies to the C135 family, the key difference being that it was a far superior airframe to begin with, and is therefore a much better long term prospect than the Nimrod ever could be...
Also worth noting that even during the second world war, the range of aircraft was negligible, ships where therefore a necessity for getting equipment from A to B. Now, if you need to get boots on the ground sharpish, a handful of C17s will get troops and their gear into theatre before HMS Ocean has left the Solent.