Within the lists of British nobility headed by the Royal family, only a Duke is deemed senior to that of a Marquess.
The title of Marquess of Queensberry, a member of the Scottish peerage, has been held by a branch of the Douglas family since 1682, being bestowed upon them by King Charles II of Scotland. The Douglases also held the title of Duke of Queensberry, until 1810 when it was inherited by the Duke of Buccleuch.
This occurred due to a previous inheritance precedence (charter of novo damus) set up by James Douglas 2nd Duke of Queensberry (1672-1711), former Secretary of State for Scotland, whereby a special remainder to the heirs, male and female of the 1st Earl of Queensberry was brought into play. This meant the title Duke of Queensberry was passed to the 3rd Duke of Buccleuch in 1810, through the female line going back to the 2nd Duke of Queensberry. Meaning the inheritance came through a daughter of the Douglas female bloodline.

The ancestral family seat of the Marquesses of Queensberry was Kinmount House in the parish of Cummertrees, Annandale, Dumfriesshire, Scotland. This was sold by the 9th Marquess in 1896 although the traditional burial ground in Cummertrees Parish Church still remains. The 9th Marquis is better known for his introduction and patronage of what was to become, the Queensberry rules still used in international boxing.
The current holder of the title is David Harrington Angus Douglas, 12th Marquess, eldest son of the 11th Marquess, with his eldest son, Sholto Francis Guy Douglas, currently holding the title Viscount Drumlanrig, as heir apparent to the marquessate
The feudal barony of Drumlanrig has been held by a Douglas for hundreds of years but it wasn’t until the 9th of Drumlanrig that the title; Earl of Queensberry was given in 1633, 5 years after the now subsidiary title of Viscount of Drumlanrig was made. The first to hold the Earlship was Sir William Douglas, killed in action in 1427 while fighting on the side of the French against the English in the Hundred Year’s War.
The question has to be, what is the link between Carruthers and the Douglases of Queensberry?
Both families are from Annandale, Dumfriesshire and are historically intertwined. But excluding the most obvious link which exists between them and led to the abuse, imprisonment and suspected murder of the last Chief of Mouswald’s daughter Marion, by James the then 7th Laird of Drumlanrig, there have been quite a few marriages between both families.
The one that played a part in and sadly led to the tragedy of the Mouswald Heiress was the 2nd marriage of Simon 8th of Mouswald and 3rd Baron, to the youngest daughter of William Douglas the 4th laird of Drumlanrig. Simon was himself murdered by the two Thomas Bells, one of Broom and one of Currie in 1504.

Another inter-family marriage that springs to mind, simply because it is based on some serious misconception, is that of an Agnes Douglas who married John Carruthers 8th of Holmains and 4th Baron.
It has been wrongly suggested, that Lady Agnes Douglas, Countess of Argyll, the first wife of Archibald Campbell, 7th Earl of Argyll and daughter of Sir William Douglas, 6th Earl of Morton had married John Carruthers. However, this is incorrect as she stayed with her husband Archibald, until her death in 1607.
John Carruthers, 8th of Holmains actually married firstly, Miss Agnes Douglas, daughter of George Douglas of Parkhead in 1600 and secondly, Janet Douglas, sister of William Douglas of Drumlanrig, 1st Earl of Queensbury in 1659.
Again in 1729, John Carruthers, 11th of Holmains and 7th Baron married Rachel Douglas, daughter of James Douglas of Dornock, who died in 1790, outlasting her husband by 56 years.
Another Carruthers-Douglas marriage, which is far more recent, was the marriage of Nigel Paul Mitchell-Carruthers to Sybil Douglas, daughter of Sholto Augustus Douglas, the son of Lord Sholto George Douglas, of the Queensberry line.

Nigel was the youngest son of Colonel Nigel Laurie Mitchell-Carruthers by his second marriage, and brother of his older sibling, Charles Nigel Simon Carruthers, father of Simon Peter Carruthers, senior of Holmains, from the Colonel’s first marriage.
Nigel himself had two children: Bruce Nigel Lawrence Mitchell-Carruthers and Cécilia Elisabeth Mitchell-Carruthers, the latter of these being the Vice Convenor of the Clan Carruthers Society International and Clan Commissioner for Europe.
Lord Sholto George Douglas was the youngest son of John Sholto Douglas, 9th Marquis of Queensberry as mentioned above.
Even though Douglas remains, like Carruthers, an armigerous clan, Cécilia being one the seniors of the line of Holmains along with her brother Bruce, can also claim descendency from one of the most senior branches of Clan Douglas itself asnd we are proud as a Society to have her on board.
Accepting this interesting link and historical intertwinning between Carruthers and Douglas, which occurs between other local families to include the Bells and Irvings to name but two, Carruthers is a Clan in their own right and is not and never has been a sept of the Douglases.