The speaker
The speaker describes a pen as being the equivalent of his father's and grandfather's spade. He is a writer, and though he speaks wistfully of his ancestors' practice, he also values his own trade. He used to take part in the potato-picking process, presumably when he was a boy or young man, for in the fourth stanza he describes the potatoes that "we picked," so some of his knowledge of the potato harvesting is from his own experience. However, he has broken from his lineage.
The speaker's father
The speaker's father digs outside his window, and the speaker thinks about how he has seen his father do this for the past twenty years. He was good at it, according to the speaker, who marvels at his father's strength.
The speaker's grandfather
The speaker looks beyond his father to his grandfather. He remembers that his grandfather was the best worker out of all the men who worked on the same bog, and he remembers witnessing his grandfather's hard work as a boy.
"We"
The speaker does not clarify who the "we" in this poem is. Possibly it could refer to the speaker and his father; however, it could also refer to siblings or other members of their family.
