I'll bow to your obvious knowledge in this area clearly I am not worthy, but could you substantiate your argument regarding the "huge amount of traffic" that Manchester handles from "outside of area" with some actual figures ? My own understanding is that these are insignificant but I am happy to be corrected.
It's about 1/3rd. So, about 6 million today and 7.5 million back in the day. Write to the CAA and ask for the supporting data from CAP 775, CAP 754, CR 07 and CR 08. There's many different but corroborating data points