Stewart of Darnley

Stewart of Darnley was a notable Scots family, a branch of the Clan Stewart, who provided the English Stuart monarchs with their male-line Stuart descent, after the reunion of their branch with the royal Scottish branch, which led to the ultimate union of the two main kingdoms of Great Britain: England and Scotland. 
In 1565 the House of Stewart of Darnley was re-united with the Royal House of Stewart when Henry Stuart, Lord Darnley married his half-first cousin, Mary, Queen of Scots, both being grandchildren of Margaret Tudor, daughter of King Henry VII of England, and hence both having claim to the English throne. The son of this union James VI of Scots succeeded to the throne of England as James I.
The later English kings of the House of Stuart, from James I and Charles I onwards, were more properly members of the Stewart of Darnley branch, and all drew upon their feudal heritage in Lennox. 
Origins and name.
The Stewarts of Darnley were descended from Sir John Stewart (d. 1298), the second son of Alexander Stewart, 4th High Steward of Scotland. Their name is derived from Derneley, a barony in Eastwood parish, Renfrewshire. It was located east of Barrhead, present day Darnley, within the city of Glasgow. In 1356, Robert Stewart, High Steward of Scotland granted the barony to Sir John Stewart, the oldest son of Sir Alan Stewart of Dreghorn. 
Like the Royal Stewarts, the Stewarts of Darnley used both the Stuart and the Stewart spelling of their surname.
Lordship of Aubigny.
Sir John Stewart of Darnley (d.1429) fought in the Hundred Years' War under his namesake and distant cousin John Stewart, 2nd Earl of Buchan in the army of Charles VII of France. For his services he was rewarded with the lands of Aubigny-sur-Nere and Concressault which were given to the second son in the family so they could live in France to strengthen the Auld Alliance.
Important members of this branch were:
The Earldom of Lennox.
The eldest son of Alan Stewart of Darnley (d.1439) was John Stewart, Lord Darnley, head of the House of Stewart of Darnley, who was created Earl of Lennox. He died in 1495 and was succeeded by the following descendants:
In 1580 the head of the House of Darnley King James VI of Scots granted the title Duke of Lennox to Esmé Stewart, 1st Duke of Lennox a cousin and a member of a French branch of the Royal Stewarts.
The following English members of the House of Stewart of Darnley were styled Earls of Lennox by the English Crown, although the King of Scots, in whose Kingdom the Earldom of Lennox lay, did not recognize their title.
Claimants to the English Throne.
In 1544 Matthew Stewart, 4th Earl of Lennox married Margaret Douglas, the granddaughter of Henry VII. Their sons Henry Stuart, Lord Darnley and Charles Stuart, 1st Earl of Lennox, were held by contemporaries to have a credible claim to the throne of England.
Margaret Douglas was the fruit of the 1514 union of Margaret Tudor, Dowager Queen of Scots and elder daughter of Henry VII with Archibald Douglas, 6th Earl of Angus. Born in England and raised at the court of her uncle Henry VIII, Margaret was Henry's officially recognized heir between the disgrace of Anne Boleyn and the birth of the future Edward VI. 
In 1565 Henry Stuart, Lord Darnley married his cousin Mary Queen of Scots, like him a descendant of Margaret Tudor and Henry VII. Mary's descent from Margaret Tudor's first marriage to James IV of Scots also placed her in line for the English throne, but many argued that Margaret Douglas's claim was superior as Margaret and her sons Henry Stuart, Lord Darnley and Charles Stuart, 1st Earl of Lennox had been born in England. According to English custom it is desirable that the monarch be naturalized or born in England. 
By marrying Darnley, Mary neutralized a dangerous rival claim to the throne of England whilst strengthening that of her own house. In 1603 Mary and Darnley's son, James VI of Scotland, succeeded Elizabeth I as King of England, thereby uniting the crowns of England and Scotland and laying the basis for the future United Kingdom.