Some shapes are just perfect. Nature grows it in sunflowers and pineapples. Flowers unfold it in their petals.
The ancient Greeks built it into their Parthenon, the French used it in their Cathédrale Notre-Dame de Paris. Madame La Gioconda shows it to great effect. Dali's Last Supper In a Geometric Bay Window practically reinvented the perfect shape.
In fact, you can even separate the shape into two bits - a unit square, and the same shape again!
You'll need your treasure map - the cache is hidden in the perfect shape, in the three square miles highlighted here:
Just focus in where the numbers go, and you'll be g...reat.
FTF goes to ... the ScotHogs!
There is parking nearby, but not very nearby. Try to either leave or enter the vicinity from the west.
The puzzle is defined in terms of longitude and latitude - converting to OS coords will lead to a non-grid-oriented shape. The solution checker admits solutions upto 10m out.
Tiles by Stamen Design under CC BY 3.0. Data from OpenStreetMap, under CC by SA.