James Stuart was the first Scottish King to also sit on the throne of England. Scottish and English affairs would be bound ever more closely together through the Union of the Crowns, but the two countries remained constitutionally separate, and significant religious differences would ensure that relations were not always harmonious.
James succeeded by virtue of his mother's descent (a great-granddaughter of Henry VII) and his Protestantism. While England had moved towards Protestantism from 1534 onwards, Scotland had remained Catholic until the dominant French Guise faction was overthrown in 1559 and a Protestant Reformation affirmed by the Scots Parliament the following year. However, because Scotland had embraced Protestant Reform at this later stage, it tended to favour a more radical Presbyterian Calvinism (articulated by John Knox) which swept away government by bishops and archbishops and replaced it with government by ministers and elders.
While England and Scotland were both Protestant after 1560, this differing approach to ecclesiastical government (and the generally more thorough nature of Scottish Protestantism) would lead to problems in the future. However, in the tense world of 1600-03 (when Europe was religiously divided and Elizabeth was dying without issue) it counted for relatively little and James's accession was secured. While Protestantism established itself in the towns and villages of the centre, borders and east coast, the more remote Highlands and islands of Scotland remained Catholic for some time to come.
James VI/I and Elizabeth I differed from each other in a number of respects; Elizabeth knew how to manage and manipulate Parliament and ensured the representation of her views through a number of privy councillors; James never really grasped the art of managing the larger, more variegated English legislature and would lecture the Commons at great length on the Divine Right of Kings which he defended. Elizabeth was parsimonious and frugal; James was lavish and a spendthrift.
James and his Parliaments quarrelled over finance, foreign policy and each party's perceived rights and prerogatives. Within five years of James's ascension, Crown indebtedness stood at £600K and the royal deficit was running at £200K annually. When Parliament proved unwilling to grant James the supply needed to make good this deficit, James resorted to raising funds through non- Parliamentary means, such as the sale of monopoly licences, import and export duties, selling peerages etc, reinforcing his moves through court decisions. While not technically illegal, James's actions angered Parliament and offended its presumed right to monitor, approve and endorse Crown expenditure. Without a clear set of guidelines to clarify each side's prerogatives and privileges (i.e. a constitution), friction was almost inevitable.
When James found Parliament difficult, he tried to govern without it and, save for the brief 'Addled (sterile) Parliament' of 1614, Parliament did not meet between 1611 and 1621. James's son Charles would try to emulate this.
When Parliament met again in 1621, Europe was embroiled in the Protestant-Catholic strife of the Thirty Years War and James's son-in-law (the Protestant Elector Palatine) had been expelled from his own lands. However, instead of rushing to defend members of his family in this war, James actually favoured a pro-Spanish policy during this period and tried to marry his son off to the Spanish infanta. When Parliament met in 1621, it criticised James's foreign policy and attacked his dubious methods of raising funds. When this Protestation was placed in the Journal of the House, James ripped the Protestation from the Journal with his own hands, arrested some dissident MPs, and dissolved the Commons- the shape of things to come.
When Parliament met again in 1624, the Protestant cause was under even more pressure and marriage to the infanta had been rejected in the most humiliating terms, so James and Charles joined the House in calling for war with Spain. Money was granted to support this strategy but James had to agree to prosecuting a less costly naval war only and had to surrender one of his ministers to calls for impeachment. When Charles took the reins of power in 1625, he faced a House which was increasingly assertive of its perceived 'rights' and was locked into a European war which was both financially costly and politically tricky. To demonstrate its strength, Parliament refused to grant Charles rights to the taxes known as Tunnage and Poundage which were normally granted to new monarchs on their accession.
As a Scottish Protestant who survived a Catholic assassination attempt (the 1605 Gunpowder Plot), James experienced only minor religious difficulties during his reign, but two things are worth noting here.
Firstly, Puritanism continued to grow in numbers and in zeal. The same Puritans who had been offended by Elizabeth's moderation were also offended by James' support for bishops, his relaxed sabbatarianism and his unwillingness to harass Catholics. So great was the zeal of these Puritans that some (the Pilgrim Fathers) actually left their own country and risked all in the colonies of the New World so that they might enjoy the 'godly commonwealth' which they desired. In time, some Puritans would seek to establish a 'godly commonwealth' at home.
James also offended the Scots in 1618 by forcing the re-introduction of bishops and by supporting the re-introduction of some practices (such as kneeling while taking communion) that smacked of 'popery'. These moves created so much opposition that they were never, in practice, enforced and 1619 plans to introduce the English Prayer Book to Scotland were quietly shelved. James' son would prove to be less flexible.
James vigorously and systematically pursued the plantation policy in Ireland throughout his reign. Following the 1607 Flight of the Earls, huge tracts of land in Ulster (3.8m acres) became 'free' and James gleefully assigned them to Scottish and English merchants, institutions and colonists.
Of course, the increasing immiseration of the locals which this caused-and the rising antagonisms between the 40,000 Scottish Presbyterians in Ulster by 1618 and the indigenous Irish and old English settlers- created the grounds for later unrest. By the end of James's reign, Ireland was an ethnic and religious time-bomb on a very short fuse.
Mounting tensions in Ireland, increasingly assertive Parliaments, rising Puritan intransigence and a Scotland determined to defend Presbyterianism - these constituted James' political legacy to his son. Only a very flexible and talented monarch could hope to keep all these forces in check.
As the impoverished Scottish monarch, James looked forward to moving south as he hoped it would give him access to a bigger public purse. James certainly had a bigger household to maintain than Elizabeth I but his tastes in all things were more lavish. Crown indebtness rose steeply during his period of rule.