Standing crowned and bejeweled Buddha

In Siam most standing crowned and bejeweled Buddha images with both hands raised palms outward seem to have had associations with ancestors, especially royal ancestors. In the reigns of both Rama I (1782-1809) and Rama III (1824- 1851) such images were dedicated to royal fathers and other relatives.

This image's crown has a removable, separately cast, upper part. Beneath the crown there is a finished chamber at the top of the head. Its purpose is not known: Perhaps it was intended to hold relics of a deceased person. But would the relics of a mortal person, even a king or a high-ranking monk, have been of sufficient status to be placed in the head of a Buddha image?