Major James Brooks of Minden Cottage on the River Lyner in south-east Cornwall is a character from the previous novel Harry Revel, which is set in the Plymouth-Rame area in 1811-12. Although there are chapters in Harry Revel set at Minden Cottage, Harry Brooks is not mentioned, nor is Harry Revel in Poison Island, which is set in 1813-14. In both novels, Major James Brooks is described as a veteran of Sir John Moore's Galicia campaign of 1808. Brooks was a major, under Lord William Bentinck, in the 4th (King's Own) Regiment, serving with distinction in the evacuation of Corunna. He returns blind on the Londonderry transport and contracts rheumatic fever on the storm-bound trip (see the short story 'Roll Call on the Reef' in the collection of the same name). On landing at Plymouth he is taken to Minden Cottage and nursed by his daughter Isabel, but never regains his sight. Released from the army on a service pension, he spends his time translating the Aeneid with the help of Harry Revel and then Harry Brooks. In Harry Revel we hear nothing of Captain Branscome of the Londonderry and nothing about a second marriage.
Major Brooks' first wife died in 1792 during the birth of Isabel, with the Major never fully recovering from the loss. In 1811, without properly informing her father, Isabel weds Lieutenant Archibald Plinlimmon, who is promptly despatched to the Tagus. During the battle of Cuidad Rodrigo, in January 1812, Archibald learns of the death of Isabel during childbirth, and himself dies at the battle of Badajoz a few months later.
Between the death of his wife and the marriage of Isabel, James Brooks marries for a second time. It is presented as a marriage of convenience, with the woman looking after Isabel while Brooks is soldiering. They have one son, Harry Brooks, who must have been born about the time of the Peace of Amiens. Otherwise, they live apart, with Amelia Plinlimmon subsequently taking on the role of foster mother for Harry. Amelia Plinlimmon is aunt to Archibald Plinlimmon. With her move from an orphanage she becomes housekeeper to James Brooks following the death of Isabel.
James Brooks appears to own Minden Cottage. The cottage is placed three miles to the west of St Germans, on the Torpoint to Liskeard road. In Harry Revel it seems to be closer to the village of Antony.
The Major is a student of the Aeneid, one of the classical references in the novel. He is translating it into English. With the death of Isabel his reading tends to the Bible.
Major Brooks spends much of his time in a summerhouse in the grounds, accessible from three directions. There he receives Branscome and Coffin, who both make their entries from a lane off the main road. He keeps his cashbox in his bedroom. On May 12, 1813, he makes a gift of ten guineas to the penurious Captain Branscome, whom he had known as the captain of the Londonderry, carrying the cashbox from the bedroom to the summerhouse. Later, Coffin arrives with the treasure map of Mortallone, which he hides in the summerhouse and which is subsequently discovered by Harry Brooks. After the departure of Coffin he is murdered by Aaron Glass who is seeking the treasure map. The nobility of Brook's character makes his murder by Glass a particularly heinous act.
Brooks is a soldier who appears never to have adjusted fully to civilian life and hankers after his former trade. The loss of his first wife is something he never recovers from. There remains a mystery regarding the second marriage and the indifference of Brooks to his son which the novel never resolves. Brooks, therefore, is not without his flaws.