Topic summary
Co-king
Extracted from the Wikipedia article Coregency.
Britain
King Henry II of England installed his eldest surviving son, also named Henry, as junior king. Henry the Young King was not permitted to exercise royal authority and his title as co-king was effectively a sinecure to denote his status as his father's chosen heir. Young Henry predeceased his father without ever ascending to the throne and is not included in the official list of English monarchs.