Anyway onto the point at hand, I thought 707s in reality have only marginally more capacity than 465/466s?
Using the figures from the South Western & South Eastern franchise agreements, 10x707 is 1182 total capacity whilst a 10 car networker* is 1153. Depends how reflective of reality the standing numbers are (640 vs 289 respectively) and how 'easily' the train can be loaded past that point
*not including 465/9