She was married secondly to Sir Colin Campbell, heir presumptive to the earldom of Argyll. When he succeeded his brother as the 6th earl in 1573, Agnes was henceforth styled Countess of Argyll. During her second marriage, Agnes became embroiled in a litigation over Queen Mary's jewels which had earlier fallen into her keeping. It was her refusal to hand the jewels over to the Scottish Government that sparked a feud between the Earl of Argyll and the Regent Morton.
