There are many graves with both head and foot stones, logically that's how they became known as headstones, and I've come across at least 2 with the details on the foot stone, rather than the head.

It might have been done to confuse grave robbers, although stones were usually left until the ground had settled a while....

Wandering round churchyards (in search of family members, genealogy) you see all manner of shape and size and style. Maybe he just wanted to be different and at least it would make him conspicuous to someone who was looking for it..

(Sorry, it's early, I'm still in BS mode!)

LTS