Answer:
Compound subject
Step-by-step explanation:
We find a compound subject when two or more nouns act as the subjects of a sentence. These individual subjects are often joined by a comma or by a coordinating conjunction like or, nor, and or neither. "Sir Edmund" and "his son, Cecil," are the nouns that are mainly discussed in and described in the sentence, thus, they are "the subject." and they form a compound one.