when mary was captured at the battle of carberry, melville took elizabeth's letters to her at lochleven castle and brought her requests to the confederate lords and her supporters. on the day that james vi of scotland was crowned he wrote to elizabeth that her ambassador nicolas throckmorton had helped defuse the situation and save mary's life. melville worked for regent moray, and arranged with sir valentine browne, treasurer of berwick, for loans of money secured with pledges of mary's jewels. however he supported mary at the battle of langside in 1568. after mary fled to england he brought jewels, clothing, and horses to her at bolton castle. subsequently, he joined his nephew william kirkcaldy of grange who held edinburgh castle for mary. at the end of the "lang siege" of the castle he was imprisoned at holyroodhouse and at lethington castle (now lennoxlove.)