On April 11, 1689 William III and Mary II were crowned as joint sovereigns of England, Scotland and Ireland, the only time in British history when two sovereigns sat upon these thrones.
Generally when a Queen Regnant mounts the British throne her husband will not share her royal title. Elizabeth I never married and the husbands of sovereign queens Anne, Victoria and the current reigning monarch, Elizabeth II, were never made King Consorts. Although Scotland is different where Henry Stuart, Lord Darnley, was made King Consort of Scotland upon his marriage to Queen Mary I of Scotland.

Mary I, Queen of England and Ireland
However, twice in English history the husbands of a reigning Queen Regnant were granted the title “King of England” but there were differences. One was a full sovereign and the other was a consort. Ironically, these were the spouses of Queen Mary I of England and Ireland and Queen Mary II of England, Scotland and Ireland.
Let me explain further….
In 1554, Mary married the future King Felipe II of Spain, becoming queen consort of Habsburg Spain on his accession in 1556.
Under the English common law doctrine of the day, jure uxoris, the property and titles belonging to a woman became her husband’s upon marriage, and it was feared that any man she married would thereby become King of England in fact and not just in name. An Act of Parliament was passed to address this issue. The Act that was passed was the Queen Mary’s Marriage Act and it was given Royal Assent in April of 1554.
While Mary’s grandparents, Fernando II-V and Isabella I of Castile and Aragon (Spain) had retained sovereignty of their own realms during their marriage, there was no precedent to follow in England. Under the terms of Queen Mary’s Marriage Act, Felipe was to be styled “King of England” on all official documents (including Acts of Parliament) and all such Acts of Parliament were to be dated with both their names, and Parliament was to be called under the joint authority of the couple. However, Felipe was not granted the title of King of England for his lifetime, it was for Queen Mary’s lifetime only.
Further stated in the Act, England would not be obliged to provide military support to Felipe in any war, and Felipe could not act without his wife’s consent or appoint foreigners to office in England. Felipe was unhappy at the conditions imposed, but he was ready to agree for the sake of securing the marriage. He had no amorous feelings toward Mary and sought the marriage for its political and strategic gains; Felipe’s aide Ruy Gómez de Silva wrote to a correspondent in Brussels, “the marriage was concluded for no fleshly consideration, but in order to remedy the disorders of this kingdom and to preserve the Low Countries.”

Felipe II, King of Spain, Portugal, Naples and Sicily, Archduke of Austria and Duke of Milan. King Consort of England and Ireland.
In reality, Queen Mary’s Marriage Act seems to have served as a business contract between England and Spain; it specifies what Spain could expect from the union, while at the same time assuring the English that England would not become a satellite of Spain.
Although Felipe was a King Consort of England and Queen Mary was the sovereign, his position was not the same as other husbands of reigning queens. The arrangement under Queen Mary’s Marriage Act did give Felipe some limited power and authority.
The Act stated that King Felipe (Philip) would take part in governing Mary’s realms while reserving most authority for Mary herself. Formally, King Philip was to co-reign with his wife according to the Act, which nevertheless ensured that the new king would not become too powerful by prohibiting him from appointing foreigners to any offices, taking his wife or any child that might be born to them outside her realm and claiming the crown for himself should he outlive his wife. (Montrose 2006, p. 46).
William III and Mary II.
James II-VII inherited the thrones of England, Ireland and Scotland from his elder brother Charles II with widespread support in all three countries, largely based on the principle of divine right or birth. In June 1688, two events turned dissent toward the Catholic king into a crisis; the first on June 10 was the birth of James’s son and heir James Francis Edward, threatening to create a Catholic dynasty and excluding his Protestant daughter Mary and her husband Willem III of Orange.
The second was the prosecution of the Seven Bishops for seditious libel; this was viewed as an assault on the Church of England and their acquittal on June 30, destroyed James’s political authority in England. Anti-Catholic riots in England and Scotland now made it seem that only his removal as monarch could prevent a civil war.

William III, King of England, Scotland and Ireland. Prince of Orange, Stadholder of the Netherlands
Representatives of the English political elite invited Willem III of Orange to assume the English throne; after he landed in Brixham on November 5, 1688, James’s army deserted and he went into exile in France on December 23. In February 1689, Parliament held James II-VII had ‘vacated’ the English throne.
Willem (William) summoned a Convention Parliament in England, which met on January 22, 1689, to discuss the appropriate course of action following James’s flight. William desired the throne but felt insecure about his position; though his wife preceded him in the line of succession to the throne, William wished to reign as king in his own right, rather than as a mere consort. William further demanded that he remain as king even if his wife were to die. As mentioned above, the only precedent for a joint monarchy in England dated from when Queen Mary I married Felipe II of Spain. Felipe II remained king only during his wife’s lifetime, and restrictions were placed on his power.
The English Convention Parliament was very divided on the issue. The radical Whigs in the Lower House proposed to elect William as a king (meaning that his power would be derived from the people); the moderates wanted an acclamation of William and Mary together; the Tories wanted to make him regent or only acclaim Mary as queen. Furthermore, Mary, remaining loyal to her husband, refused to reign on her own without her husband.
Mary II, Queen of England, Scotland and Ireland.
The House of Commons, with a Whig majority, believed that the throne was safer if the ruler were Protestant. The Commons made William accept a Bill of Rights, and, on February 13, 1689, Parliament passed the Declaration of Right and the Crown was offered to William III and Mary II as joint sovereigns. It was, however, provided that “the sole and full exercise of the regal power be only in and executed by the said Prince of Orange in the names of the said Prince and Princess during their joint lives.” In other words, even though both monarchs were sovereigns (and neither a consort of the other) William was given the majority of executive power.
William III and Mary II were crowned together at Westminster Abbey on April 11, 1689 by the Bishop of London, Henry Compton. Normally, the coronation is performed by the Archbishop of Canterbury, but the Archbishop at the time, William Sancroft, refused to recognise James’s removal.
William also summoned a Convention of the Estates of Scotland, which met on March 14, 1689 and sent a conciliatory letter, while James sent haughty uncompromising orders, swaying a majority in favour of William. On April 11 the day of the English coronation, the Convention finally declared that James was no longer King of Scotland. William II and Mary II were offered the Scottish Crown; they accepted on May 11.