He studied at the universities of St. Andrews, Glasgow, and Paris, and was at the French court in 1519 as Scottish "resident", then twice later as ambassador to negotiate James V's marriages. In 1525 he took his seat in the Scottish Parliament as Abbot of Arbroath and was appointed Privy Seal. Made a cardinal in 1538, he became Archbishop of St. Andrews. 
On James V's death, he produced a forged will appointing himself and three other regents of the kingdom during the minority of Mary, Queen of Scots. However, the nobility elected as regent the Protestant Earl of Arran, who was to inherit the crown if Mary died. Beaton was  arrested, but soon regained favour and in 1543 was made chancellor. One of the potent clerical statesmen of high intellect which the 16th century frequently produced, he was at first the Earl of Arran's antagonist, but quickly appreciated that he had to work with him. Consequently they forged an alliance which ruled Scotland and endured unbroken until the assassination of the cardinal. 
His private life centred around a seemingly accepted association with Mariota Ogilvy, daughter of the first Lord Ogilvy, who bore him five sons and three daughters in a stable relationship lasting more 
than twenty years. The Cardinal made many grants of land to Mariota and her family and also provided for the future careers of his sons. Mariota survived the cardinal by thirty years. 
1543 was a year wasted by Henry VIII; he should have invaded Scotland but frittered away his chances by trying to arrange a marriage between his son and Mary, Queen of Scots. However, once the 
campaigning season was over, Arran rejected the marriage proposal. Henry VIII had amassed a huge army but, in 1544, was engaged in warfare with France. 
However, in May 1544 on Henry VIII's behalf, the Earl of Hertford invaded Scotland and this war was later entitled as "the rough Wooing". However, this was little more than a hit and run raid, designed to prevent the Scots from threatening northern England while Henry VIII was in France. 
Even though this invasion had caught Beaton and Arran unprepared, it only stiffened Scottish hatred of a union with England. Arran suffered politically and lost the support of a considerable part of the governing class. 
The Earl of Arran came to an arrangement with Marie de Guise, the queen mother, who had threatened to challenge his claim to power. However, February 1545 brought a stunning Scottish victory at 
Ancrum Moor and in May a sizeable French force landed at Dumbarton and was soon threatening northern England. However, in September 1545 an English force invaded Scotland but this lasted only three weeks and was without any results. 
Henry VIII, enraged against the Scots, plotted against Beaton and tried to seduce disaffected nobles. He induced the Emperor Charles V to declare war on Scotland but it was all to no avail. Beaton and 
Arran adamantly refused a betrothal between the infant Queen and Henry VIII's son which was to produce the union of England and Scotland. 
Early in 1546 the cardinal, in order to provide himself with a much-needed triumph, arrested the Protestant preacher George Wishart. After a trial, Wishart was condemned and burned at the stake at St. Andrews on 1 March. However, three months later Wishart was to be revenged: in May 1546 while in his castle of St. Andrews, Cardinal Beaton was murdered by conspirators. They hung his blood-dripping corpse in the shape of a St. Andrew's Cross outside a window of his castle. 
In January 1547 Henry VIII died. The œ350,000 he had spent in his wars against Scotland had bought the tower at Langholm and an understanding with the "Castilians" who had taken over St. Andrews 
Castle. By July 1547, both were back in Arran's hands.
 

Source: Leo van de Pas