Distance to airports

When they measure the distance from an airport for the no fly zone, is it from the control tower or the runways?
I live about 3.5 miles from the control tower at Liverpool as the mavic flies and there’s a few things local I want to fly over.

I always took the 5km from edge of closest runway.

Saying that I have no idea what’s going on now with the new regulations and the 1 km from boundary thing.

The new regulations are from the perimeter fence


So legally is it only 1km?

Where did the 5km in drone code come from? Or was that just a guideline?

I did see an interview on TV where they were complaining that 1km from the perimeter fence of an airport wasn’t far enough as planes still can be below 400ft at 1km out and therefore still a ‘near miss’ risk !
Pretty sure 1km is the legal distance within which you can receive unlimited fine and prison sentence!

I believe a guideline.

How close to my local airport I fly depends on …
a) how close to the extended runway centreline I am, and
b) which way they are taking-off/landing.

I give them a far wider space on approach where the default glidepath is ~3 degress and always landing close to the beginning of the runway.
Some planes, these days, actually leave the ground before the midpoint of the runway and climb at ridiculous angles, so far less of a problem at that end of the runway.