The boiled egg that is planet earth...
What an inspired thread!
Just to clarify - 'North of' means just that. Unless you are treating the earth like a boiled egg, ie carefully lopping off the cap at latitude 58 north, then D703/15 extends to the true north pole.
As Thom (peace be upon him) notes, these are all in a Northerly direction - the British Isles being designed this way means that cartographers can save on chart congestion and ink!
I wouldn't fly within a gnat's knacker of this latitude, but it does mean at the planning stage I know where to look on my chart for the midden and if, in this case, I am flying between latitudes 52 and 53 I can strike a line through that NOTAM entry without looking further.
BUT...
If the area is circular, is the datum point set at the centre of the circle or still, as is logical, at the lowest whole latitude? I am beginning to scare myself here!