Pray tell, why would MI6 use an airliner that was unlikely to get anywhere near sensitive installations? How could they fit reconnaissance equipement to the plane without it being obvious? Do you think they had someone using a digital camera snapping pics through one of the windows? I can get better images of IAF bases on Google Maps!
Russia: U.S. plan to provide air cover for Syrian rebels undermines Damascus fight on ISIS (Reuters)
from the article: Revealed: Passenger plane nearly crashed into IAF fighter jet