Before 23 July 1587 he was ordained minister of St. Cyrus or Ecclesgreig in Kincardineshire, and had at the same time the church of Aberluthnott, or Marykirk, also under his care. During his residence at St. Cyrus he was on several occasions in danger of his life from armed attacks on his house by William Douglas the younger of Glenbervie and others, but was relieved by the exertions of his neighbours.
Gladstanes was a member of the general assembly of 1590 (Scot, Apologetical Narration, Wodrow Soc., p. 57). In May 1592 he was presented by the king to the vicarage of Arbirlot in Forfarshire, and was again a member of assembly in that year, and also in 1595, when he was nominated with several others as assessors with the king in the choice of two royal chaplains. About this time he served on several commissions appointed by the general assembly, one of which was for advising with the king on church affairs. The ministers in St. Andrews, Messrs. Black and Wallace, having offended by their preaching, the king ordered them to be summarily removed from their charge, and brought Gladstanes from Arbirlot to fill their place. He was inducted at St. Andrews on 11 July 1597, James Melville very reluctantly preaching on the occasion.
When the king in the following year introduced the proposal that the church should be represented in parliament, he was warmly supported in the assembly by Gladstanes, who was appointed one of three commissioners chosen to sit and vote in parliament in name of the ministry. He became vice-chancellor of the university of St. Andrews in July 1599, and on 14 Oct. 1600 was made bishop of Caithness by the king. He sat in parliament as bishop, and was challenged by the synod of Fife, meeting at St. Andrews 3 Feb. 1601, for doing so, when he declared he was obliged to answer ‘with the name of Bishop put against his will, because they would not name him otherwise’ (Calderwood).
Gladstanes continued to be minister of St. Andrews. He was employed by the assembly on various commissions for dealing with the papists, for the plantation of kirks, and for visiting presbyteries. On 24 Nov. 1602 he was admitted a member of the privy council of Scotland, being the second clerical member of that body, and after the accession of James VI to the crown of England was appointed in 1604 one of the commissioners for the union of the two kingdoms. He went to London in the latter part of that year, but before starting he, along with his brethren of the presbytery of St. Andrews, renewed the national covenant, or Scots confession of faith, and subscribed it. When at London, on 12 Oct. 1604, he was appointed by James VI archbishop of St. Andrews; but on his return, fearing the displeasure of his co-presbyters, he did not disclose what had taken place. At a meeting of the presbytery on 10 Jan. 1605 he openly declared that he claimed no superiority over his brethren. Some of his friends asked him, according to Calderwood, how he could bear with the presbytery. ‘Hold your tongue,’ he replied; ‘we shall steal them off their feet.’
Gladstanes long refrained from assuming the title of archbishop of St. Andrews. The king required him to resign the old archiepiscopal residence of the castle of St. Andrews, in order that it might be conferred on the Earl of Dunbar, and Gladstanes resigned it formally both at Whitehall and in the Scottish parliament. He received in exchange the provostry of Kirkhill, &c., with an annual pension of three hundred merks (13l. 6s. 8d. sterling). James also compelled him to yield another of the old primatial residences, Monimail, Fifeshire, in order that he might confer it on Sir Robert Melville of Murdocairnie. Gladstanes then obtained a few vicarages in Forfarshire. But at a later date the king purchased back the castle of St. Andrews as a residence for the archbishops of St. Andrews, and Gladstanes dwelt in it for a time.
Gladstanes had a great aversion to Andrew Melville. Martine states that the king brought Gladstanes to St. Andrews, where Melville was principal of the university, for the very purpose of balancing and putting a check on Melville, and of preventing the students from imbibing Melville's principles. ‘And,’ he adds, ‘many a hote bickering there was between them thereupon’ (Reliquiæ Divæ Andreæ). In a letter to the king on 19 June 1606 Gladstanes says: ‘Mr. Andrew Melvil hath begun to raise new storms with his eolick blasts. Sir, you are my Jupiter, and I under your Highness, Neptune, I must say, Non illi imperium pelagi … sed mihi sorte datur. Your Majesty will relegat him to some Æolia, ut illic vacua se jactet in aula.’ James commanded Melville with certain others to appear before him in London, and he was never permitted to return to St. Andrews. The ostensible occasion of the summons was the king's desire for the conference at Hampton Court, which Gladstanes also attended as one of the representatives of the bishops (22 Sept. 1606). Before going he promised the presbytery of St. Andrews that he would do nothing ‘to prejudice the established discipline of the church.’ The presbytery, however, supplied to Andrew Melville documents to show that Gladstanes had signed the