March, 1811, he married Elizabeth Browne, but within a few years satisfied of their utter incompatibility, they very amicably, on both sides, arranged for independence of each other. She was said to be addicted to writing sermons at night to the disturbance of the slumber of her rollicking spouse. The fault was certainly not hers, for she was a clever and exemplary woman. She lived nearly as long as he did, but they rarely met, though he made repeated overtures to reconciliation, some rather amusing. It is the reasonable ambition of all Englishmen, whose conditions and circumstances justify such aspirations, to be permitted to take part in the legislation and government of the country, and when Sir Isaac's health and peace rendered active service in the navy no longer desirable, his wish was gratified by his return to Parliament in 1818 for the borough of Ilchester for which he sat till 1826. His reputation and experience, gave considerable weight to his opinion when he took part as he frequently did in debates on naval affairs. He was tall, robust, but of symmetrical proportions, his voice powerful, and his countenance expressive and noble. Sir Isaac died at Cheltenham in Gloucestershire, June 23, 1839, at the age of 80. Lady Coffin preceded him to the tomb on the 27th of January that year. His brother, General John Coffin, died the year previous, June 12, 1838, in New Brunswick. Sir Isaac made frequent visits to his native town, having made more than thirty voyages to and from America. The many brilliant gentlemen of Boston in professional life, or among its merchant princes, affluent and convivial, were pleased to have him as their guest. Loyalty to the mother country died out slowly, and a Boston born boy, who had attained great distinction, whose kinsfolk had ample means for hospitality, had much attention paid him. His kinsman, Thomas C. Amory writes, "Often when at my father's, who resided in Park street, where now is the Union Club house, the festal entertainments extended into the small hours, and those upon whom it devolved to sit up to receive the roisters, would gladly welcome from far off his shout of 'Home ahoy!' breaking the silent watches of the night." His prize money amounted to considerable. This he entrusted to his cousin Amory in Boston, and the income finally equalled the original deposit.