On the MR4 most of the really clever stuff, the mission electronics is subbed to Boeing anyway leaving a fairly straightforward upgrade to the engines and airframe of an admittedly fragile and apparently carelessly assembled vintage airframe, but something BAE should have been able to manage on its own with little problems
I think you could describe some of De Havilland's manufacturing processes as quaint but certainly not "careless".
That's a very long sentence. You'd rarely get more for murder.