Ok let's put this to bed for once and all
infiniti didn't and haven't built anything !!!
The site for the plant was chosen in 1983
And handed over to nissan in 1985, the bluebird being the first project.
Since then it's continuously expanded into the biggest car plant in the UK...Nmuk is massive they press the body panels from coil sheet..weld them into body in whites , paint on site , build some of the engines in house casting the blocks then assemble the entire car.
Half a million units per annum, for infiniti they just extended the main lines , put in new facilities as it's a more complex build
hope that explains it.