Yes, I think we did do that, back in the days when we were looking at Stonehenge/Glastonbury/Lundy alignments and the like.
I've added an extended version of that same longitude to our CartoDB map.
As best I can judge, it goes from the western tip of the Shetlands, as you'd expect down through Britain, across France (joining a way west of Mont St.Michel, departing near Les Sables-d'Olonne (some way east of Carnac, but near La Roche sur Yon and La Rochelle), reaching Spain at Irun, deaprting near Garrucha, and then down to near Ghazaouet in Algeria.
Out of curiosity, I did try projecting further south as far as latitude 30 (as per the Great Pyramid at Giza) but I was figuratively lost in the Sahara Desert, with nothing to see but sand.
See https://tme.cartodb.com/viz/9e11e430-2f ... 54a1cb/map