Why Is the Eton Collar Such a Weird Shape?
In the detachable collar world there is no collar quite as unique as the Eton Collar. It is one of the few stiff collars specifically designed to ride outside, and over the top of, the wearer's jacket - a feat that required quite a deal of engineered thinking from it's designer.
Depending on what source you reference, the Eton Collar was introduced to English society anywhere between 1820 to 1875. Part of a school uniform for junior students, its application over the jacket collar set it apart from the senior student's uniform which was a simple stiff standing winged collar design.
Besides what the viewer sees from the outside, it is inside the collar that the real genius is revealed.
The design of the Eton ensures that the jacket's rising collar is not crushed nor causes an apposing force against the collar.
Therefore, the collar incorporates a design which creates quite a bit of space and spread under it into which the jacket's collar can be inserted. The collar on its own appears to be quite strange, but once coupled with the jacket it takes on it's intended form and makes perfect sense.
Thus the collar sits neatly over the jacket collar.