As someone who travels regularly from Formby to our Daughter's in Northumberland,using the A69,& have been doing also since she started medical school in 1993,I have experienced the change in road markings over the years on this specific road when all of a sudden virtually the whole stretch had broken external & hatched central markings applied over red tarmac,including many junctions.
I was driving a succession of Rover Honda V6 Vitesse's,then a Vitesse Turbo Sport,& now a BMW 530D all tweaked & well capable of leapfrog overtaking very quickly & safely the many & varied slow moving trucks ,Toyota Auris's ,towed caravans & making a long journey tolerable.
Getting the same reaction from oncoming vehicles usually not only flashing but prolonged fullbeam at night,& movement towards the road centre,or the sudden acceleration to close the gap when being overtaken with the fist shaking etc,I checked the Dept of Transport Road markings handbook very thoroughly & this confirmed that the official meaning is that provided it is safe to do so,the full road can be used without exception so this obviously also covers these markings at junctions also.
It seems most of these ex flat capped Morris Minor drivers are not aware of the ruling so I am still very careful .
The main problem is being able to see clearly where solid line are sometimes substituted from a distance when making the decision to overtake,particularly at night.
However,have now switched to using the Military road from east of Brampton since she moved further North to near Morpeth-virtually no other traffic,engage cruise control & remember to slow down at the steep dips!