Thanks for your response. The idea of moving the maintenance areas to Northolt would not work. The runway is only 5,500 ft long and as such could not accommodate A330/B777 or larger.
Northolt's primary importance would be to move all smaller aircraft movements from Heathrow in order to create more landing and take-off slots for larger aircraft there.
All B737, A319/320, MD80, Dash 8, ATR etc etc movements could be shifted to Northolt.
A taxyway between the two airports isn't really practical. Much better to move the passengers (themselves) quickly via a dedicated underground link.
But overall I am happy that someone read my post and thought about it. Thank you.
