UK government wanted a new plane, but wanted to save alot of money. So, they took old bodies from aircraft about to be scrapped, and told the contractors they had to use them instead of building completely new ones.
Problem being is that when the new wings were made using modern techniques, they didn't fit (suprise suprise) and needed to be literally bent into shape and all sorts of stupidity to get them onto the bodies.
Then there was the fiasco of the bodies themselves being slightly different shapes and sizes because they were not built with modern methods. Did the uK governemt care? nope, they wanted 'value for money'. So every single one is slightly different shape and size which leads to everything inside having to be jigged around to fit and it is literally a 'make do' airframe.
so, instead of saving millions and time, it cost many millions extra for all these tailor made wings and bodies, and added 6 years to the development as each one is unique.