Used two 'Views'

Added a new View with:

Title = Taxonomy Child Nodes

Fields:
Taxonomy term: Name (Name)
Taxonomy term: Term description (Term description)

Contextual filters
Taxonomy term: Parent term

Settings (Contextual filters):
When the filter value is NOT available = Hide view
When the filter value IS available or a default is provided = Override title with %1

Second View:

Used the 'Views' default Taxonomy term
Aded a HEADER = Global: View area

Settings:
View to insert = View: taxonomy_child _nodes Display: default
Checked Inherit contextual filters