JAMB - Government (2001 - No. 25)

When Nigeria achieved independence in 1960, the Head of state was the Governor-General, representing the queen of England.
One of the main provisions of the constitution of 1960 was that the governor general was made the constitutional ceremonial Head of state and a representative of the Queen of England.

This means the queen was the head of state but appointed a representative in the person of the governor-general to stand in for her, in her absence.