The route uses white roads which cannot be automatically drawn by AutoP(i)lot.
Simply mark the beginning and end of the white and draw a straight line between the points with AutoP(i)lot temporarily switched off.
Route Card Commentary
The clue here was "Elementary".
The solution lay in utilising the Periodic Table of Elements.
This is a representation of Chemical Elements that orders elements in groups with similar properties, and in increasing Atomic Number.
This route used a part of the right hand side of the table.
So, the rightmost column of the table reading downwards is: 2, 10, 18 etc.
The table is overlaid on the map where an "atomic number" became a grid square, so "10" equates to grid square 2703, "18" to 2702, "9" to 2603, and so on.