I have just read the BBC item about the incident on the A319.
I am curious to know that if the aircraft turned over Potters Bar and Billericay to land at Heathrow why it did not land at Stansted. The airline´s main concern (and thus the captain´s) is passenger safety.
Stansted was the nearest full sized and fully equipped airport where the plane could have landed without causing too much disruption and certainly less than at Heathrow to where the passengers could have been bussed back from Stansted. Or was it a case of the pilot making sure the aircraft arrived back at base, with all the savings that involves?
I think this was an incident which only underlines the necessity of a third runway at LHR both to reduce crowding and to provide an alternative runway in case of an emergency.