His term as Minister to the United Kingdom was marked by controversy: the abolitionist cause was growing in strength, and some sections of public opinion resented the choice of Stevenson, who was a slaveowner, for this role. The Irish statesman Daniel O'Connell was reported to have denounced Stevenson in public as a "slave breeder", generally thought to be a more serious matter than simply being a slaveowner. Stevenson, outraged, challenged O'Connell to a duel, but O'Connell, who had a lifelong aversion to dueling, refused, and suggested that he had been misquoted. The controversy became public and the repeated references to slave breeding caused Stevenson a good deal of embarrassment; there was a widespread view that if O'Connell's charges were false Stevenson would have done better to simply ignore them rather than engaging in a public squabble.