And using the BA 777 at heathrow as an example is pretty lame.
What tosh: the 777 scenario was virtually identical to the OP:
PB in 777 realised he was sinking too fast with landing drag flaps out and with no power available retracted the flaps.
Reduced drag thereby gave him less sink, just enough to hop over the fence and avoid landing on buildings outside the airport.
The OP's scenario was of the pilot in a situation where on final he needed more power (which in this case was available to him unlike the 777) but chose not to use power and instead retracted the flaps and got in.
Both scenarios highly non-standard, virtually identical and not to be recommended, but both achieved a survivable result.
Cusco