Explanation of the surname Drost
Drost, the Danish name of a supreme state official who in Medieval Scandinavia was the leading man of the government.
The word that seems to be of German origin (Truchsess) means a butler or a leader of the household but during the Scandinavian Early Middle Age it developed into a powerful political position. The drost acted as a kind of a ”prime minister” who was the king’s substitute and at least officially havde leadership of other officials. Less powerful drosts often went into the background in favour of the chancellors. The office seems to have appeared in Denmark in the 1200s and a bit later in Sweden and Norway. In was not quite unusual that also minor (or local) princes like Dukes had their own drost.
In all three countries the post was abolished in the 1380s. In Denmark it was replaced by the Steward of the Realm. In Sweden it was revived in the 1400s and in the 1600s in a new version (riksdrost) ”drost of the Realm” which was also used in Denmark for a short while after 1660.
In North Western Germany the word “land drost” was used about noble district caretakers until the 1800
http://en.wikipedia.org/wiki/Drost