Kennington Plane Count Shock

A Kennington resident (SE17):

I have counted planes passing close to my home in Kennington as they approach Heathrow airport.   My count is taken from one of my windows, that is 16 miles east of Heathrow. These are my observations:

Thurs 9 November 2017:  18.10 hrs to 19.10 hrs.  I counted 50 planes at a frequency of one every 72 seconds.
This is typical of westerly landings for most of the day and evening up to about 10pm.

Sunday 19 Nov 2017:   4.30 to 5.30 pm.   A plane every 75 seconds each one keeping tightly to the same narrow corridor, heading due west a little to the south of my home.    This was going on all day from around 10 am, probably earlier:   frequency slightly less in the middle of the day.   It has been quieter since about 6pm.

The narrow landing corridor intersects with a narrow viewing corridor from my front window which faces West South-west.   A small area of sky between approx. 30 degrees and 45 degrees is visible from my sofa’s viewing point within the room and the lights of each one of the planes tracked the same path, at 40-45 degrees elevation, within this narrow area.   There is now a rebuttable assumption that all westerly landings into at least one of the Heathrow runways are being routed at low altitude along the same long narrow corridor – much longer and narrower than before.