He was invested with the lands of Ardrossan and other estates of the family 5 June 1484, and on 11 October he executed a revocation of all acts made during his minority.
On 4 July 1498, he obtained a grant of the bailiary of Cunningham, and was made chamberlain of the town of Irvine.
The former grant gave rise to a long chronic feud between the Montgomeries and the Cunninghams, earls of Glencairn.
[1] On 18 August 1533, Patrick Hepburn, 3rd Earl of Bothwell, Lord High Admiral of Scotland, appointed him admiral-depute within the bounds of Cunningham.
During the absence of the king in France in 1536, to bring home his bride, the Princess Magdalen, he acted as one of the council of regency.