Just because you happen to be close to something that might be described as a line feature - you don't have to follow it - therefore rule 19 will not apply to you.
Therefore, when bimbling in the vicinity of the M25 between LAM, BNN and BPK, you may well see aircraft that are "not obeying the rules". It has to be one of the most densely packed areas of VFR airspace in the South East.
Liberally apply rule 17.
