I worked with an engineer we head hunted from BAE and his last job there had been on the new wing for the MR4. According to this bloke the biggest issue they encountered was the new wing fitted the airframe its dimensions were taken off perfectly, the problem was no two Nimrods were the same meaning the precision designed wings were extremely difficult to fit to the remainder of the fleet. Sort of makes you wonder if it may have been cheaper to have built new fuselages as well.
A bit more whiffy, the new wing apparently had a fairly low RCS due to its clean lines, composite materials and the engines buried in the wings, just imagine what could have been done with a new fuselage and appropriate coatings.