Andrew was born in 1748. At some point, he became captain of . He married and had two children, James and Esther Blamey. However, Andrew had a reputation for being a drunk with a temper. When his wife died, some believed that he had killed her in a rage. However, it is unlikely there is any truth in that claim.
Andrew went to a dance in 1784, where he met Verity Poldark. He fell in love with her and pursued her. Verity was receptive, and they began meeting up in secret. However, when her father and brother found out, they tried to scare her by telling her of his late wife. Verity thought that he had changed and began to sneak out her home to meet him with the help of Ross and Demelza Poldark at Nampara.
However, her family soon found out and her brother marched to Nampara. Despite Verity's protests, Francis challenged Andrew to a duel. Verity screamed that she will return to Trenwith and never see Andrew again if they agree not to duel. However, they go ahead and Andrew wins, leaving Francis wounded. Andrew then leaves Verity.
Andrew and Verity would not meet again until the day of miner's riot. Demelza had invited Andrew to meet Verity in town, who was taken by surprise and run away. Andrew saved them from the riot and told Verity that he loved her and would never leave her again. They started to see each other again but she refused to tell her family. However, when Andrew showed up at the ball, he tries to speak to her brother to make him see that he had changed. When that failed, Andrew and Verity eloped.
Andrew later invited James and Esther to meet Verity at their home in Cornwall. Esther was unkind to Verity but when Andrew arrived with James, he was welcoming. The relationship between Verity and her brother improved when Andrew spoke with him, and she and Andrew welcomed their first child, Andrew, in 1793. They later moved to Portugal.