HS2 works out at an estimated £1998.32 per inch.
St Pancras to Manston = 81.2 miles (at this price, .2 is significant,) or
£8,632,672,983
That is the railway taken care of then.
Nobody seems able to explain to me why an airport in a big big field with nothing around it, (save for Andrewsfield,) connected to a motorway 20 minutes from the M25, could not be chosen instead.