You Honour,
There is 6000' in a nautical mile. It is 6nm from the restricted area EGR159 to the eastern edge of the class D airspace. LCY is 4.9nm from the edge of the airspace. I am flying at 2400' and my aeroplane has a glide ratio that exceeds 10:1.
This means I can glide for 4.0 miles from 2400'. At no time am I more than 4.0 miles from a suitable landing area - LCY or outside the Class D zone (and outside of the congested area). Damyns Hall is 7.2nm from LCY, so half way into the zone I can glide to LCY or Damyns Hall.
So you see your honour, I planned the flight taking into account Rule 5 and the ability to glide clear in the event of an engine failure.