Boeing 727's always seemed in my eyes to need more of Luton's runway to get airborne. In fact it was a Dan-Air 727 that took out some of Luton's approach lights and ILS. I seem to remember when reading the accident report that the aircraft then dropped into the valley before climbing away to head for Gatwick for a emergency landing.
It might well be the case that Luton's position on top of a hill saved the aircraft.
From the report
The aircraft appeared to get airborne just at the end of the stopway.
One observer said it seemed to him that the aircraft remained level while the runway dropped away from it. The aircraft was then seen low in the valley to the west of the airport from which position it climbed away.