What was a major reason for British concern over their interests in the Falkland Islands?

The major reason for British concern over their interests in the Falkland Islands was indeed related to Vernet's aggressive actions against others. During the early 19th century, the Falkland Islands were under the authority of a governor named Vernet, whose unilateral actions to assert control and engage in conflict with other nations and individuals escalated tensions in the region. This aggressive posture was alarming to the British, as it posed a direct threat to their claims and interests in the islands, particularly as they had established a presence there. Vernet's actions raised fears that these tensions could lead to armed conflicts or diminish British influence in a strategically significant area.

The other aspects like lack of local support, international negotiations, and naval blockades, while potentially relevant to broader context, were not as immediate in driving British concern as Vernet's behavior, which created a sense of urgency regarding the security and governance of the islands.