Think you will find that Heathport Airrow, has 12,000 ft of runway, which is over a thousand feet more than Fairford or Brize. Think Boscombe is longer than Brize and Fairford and that Bedford once was. If one assumes hydraulic issues include brakes, then the answer becomes possibly easier to grasp. Also, they have lots and lots of firecrews at Heathrow. A guess, I admit and although no fan of speculation on aviation issues, coudn't resist this one, for which I apologise.
Conan