Thomas Stewart was an illegitimate son of King Robert II of Scotland

Robert II of Scotland

Robert II became King of Scots in 1371 as the first monarch of the House of Stewart. He was the son of Walter Stewart, hereditary High Steward of Scotland and of Marjorie Bruce, daughter of Robert I and of his first wife Isabella of Mar...

. In 1380, Avignon Pope Clement VII provided Thomas with the Archdeaconry of the Bishopric of St. Andrews, as well as the canonry (and prebend) of Stobo in the Bishopric of Glasgow. In 1389, the king petitioned and obtained for Thomas from the Pope the right to hold the deanery

Deanery

A Deanery is an ecclesiastical entity in both the Roman Catholic Church and the Church of England. A deanery is either the jurisdiction or residence of a Dean.- Catholic usage :...

 of the Bishopric of Dunkeld

Bishop of Dunkeld

The Bishop of Dunkeld is the ecclesiastical head of the Diocese of Dunkeld, one of the largest and more important of Scotland's 13 medieval bishoprics, whose first recorded bishop is an early 12th century cleric named Cormac...

 along with his other offices, and in 1393, the Pope provided a canonry

Canon (priest)

A canon is a priest or minister who is a member of certain bodies of the Christian clergy subject to an ecclesiastical rule ....

 in the Bishopric of Brechin

Bishop of Brechin

The Bishop of Brechin is the ecclesiastical head of the Diocese of Brechin or Angus, based at Brechin Cathedral, Brechin. The diocese had a long-established Gaelic monastic community which survived into the 13th century. The clerical establishment may very well have traced their earlier origins...

. In this period, Archdeacon Thomas obtained a Bachelor of Canon Law

Canon law

Canon law is the body of laws & regulations made or adopted by ecclesiastical authority, for the government of the Christian organization and its members. It is the internal ecclesiastical law governing the Catholic Church , the Eastern and Oriental Orthodox churches, and the Anglican Communion of...

 at the University of Paris

University of Paris

The University of Paris was a university located in Paris, France and one of the earliest to be established in Europe. It was founded in the mid 12th century, and officially recognized as a university probably between 1160 and 1250...

.

On 1 July 1401, following the death of Walter Trail

Walter Trail

Walter Trail was a late 14th century Bishop of St. Andrews. He appears as an official in the Bishopric of Glasgow in 1378, as a Magister Artium and a Licentiate in Canon and civil law. In 1380, he is a doctor in Canon and Civil Law, as well as a Papal chaplain and auditor. In this year, Pope...

, Bishop of St. Andrews, Thomas was elected to fill the see

Episcopal See

An episcopal see is, in the original sense, the official seat of a bishop. This seat, which is also referred to as the bishop's cathedra, is placed in the bishop's principal church, which is therefore called the bishop's cathedral...

's vacancy. However, because of the problems experienced by Avignon Pope Benedict XIII, who was being besieged by the King of France, Thomas had problems obtaining Papal confirmation. In this context, Thomas' election fell victim to the political struggles of the time. Thomas was supported by his nephew, David Stewart, Duke of Rothesay

David Stewart, Duke of Rothesay

David Stewart was the heir to the throne of Scotland from 1390 and the first Duke of Rothesay from 1398. He also held the titles of Earl of Atholl and Earl of Carrick...

, who actively campaigned in the region of St. Andrews during the year 1401. However, this aligned him against his half-brother, Robert Stewart, 1st Duke of Albany

Robert Stewart, 1st Duke of Albany

Robert Stewart, Duke of Albany , a member of the Scottish royal house, served as Regent to three different Scottish monarchs...

. In order to obtain control of Dumbarton Castle

Dumbarton Castle

Dumbarton Castle has the longest recorded history of any stronghold in Great Britain. It overlooks the Scottish town of Dumbarton, and sits on a plug of volcanic basalt known as Dumbarton Rock which is high.-Iron Age:...

, the Duke of Albany offered its keeper, Walter de Danyelston

Walter de Danyelston

Walter de Danielston [Danyelston] was an early 15th century Bishop-elect of St. Andrews. Walter first appears on record in 1392 as a licentiate canon of the Bishopric of Aberdeen, studying civil law at Avignon. By 1394, Donnchadh, Earl of Lennox had presented him with control of the hospice of the...

, the semi-vacant see of St. Andrews. After a meeting between Albany and the Bishop elect at Abernethy in the summer of 1402, Thomas renounced his rights as Bishop and allowed a new "election" to take place.