The estate of Borlum is in the parish of Reay.
The estates of Toftkemp and Thura are in the parish of Bower.
In the South or "Murkle Aisle" of the parish church of Thurso there is a mural inscription on the north-west wall, in the following terms: -
"This is the burial-place of James Sinclair of Borlum; and here lyes James Sinclair his eldest son and his spouse, Eliz. Innes, who left behind them the Revd. Mr. John Sinclair who was Rector of James interred in Leckpatrick nigh Strabane in Ireland 1665".
"Here lyes Isabel Sinclair who was married to the Revd. George Anderson Minister of Halkirk; and Elizabeth Sinclair married to John Farquhr, Bailze of Thurso; and Margaret Sinclair spouse to George Sinclair in Ulgrimbeg".
Isabel Sinclair was the grand-daughter of James Sinclair of Borlum, and it is thought that Elizabeth and Margaret were probably her sisters; that all three were daughters of James Sinclair, the eldest son of Borlum, and that George Sinclair, the husband of Margaret, was a grandson of John Sinclair, first of Assery.
Who James Sinclair of Borlum was is very uncertain. He may have been a grandson of William Sinclair of Dunbeath, to whom Brubster, Brims, Toftkemp, and Borlum, Toftkemp, and Thura belonged: Borlurm's name occurs in common with all these places in the county records from 1624 to 1646 ; or he may have been of the family of Murkle, and if so, he may have been a brother of John Sinclair, first of Assery, and a son of James Sinclair, first of Murkle.
In McKay's history it is mentioned that James Sinclair of Borlum was killed (time not stated) by one Neil McKay, for the share he had in the slaughter of the latter's father in an affray in Thurso, about 1648, with which Murkle was concerned. Then, Murkle was cautioner for him and for his own son, John Sinclair of Assery, in 1637; and frequent marriages took place between the immediate descendants of Sinclair of Borlum and Sinclair of Assery. Thus, Borlum's son, Major William Sinclair, married Assery's grand-daughter, Margaret Doull; Borlum's grand-daughter, Jean Sinclair, married Assery's great-grandson, Alexander Sinclair; and Borlum's grandson, Richard of Thura, married Elizabeth, daughter of George Sinclair of Assery. It may be noticed also that James Sinclair of Murkle is found as cautioner for John Sinclair of Assery, his son, and James of Borlum, and that John Sinclair, fourth of Sybster, the son of Assery, is cautioner in 1658 in the marriage contract of Borlum's daughter, Jean.
On the other hand, if James Sinclair was of the Dunbeath family, he was probably the son of George Sinclair of Dounreay, the youngest son of William Sinclair.
It is certain, at all events, that there were transactions between James Sinclair and the descendants of William Sinclair in relation to lands which belonged to the family, Thura. In particular, there is mention of a renunciation of rights held by Borlum over Spittal, granted by him, in 1649, to John Sinclair of Brims, grandson of Dunbeath. This deed, if extant, would perhaps throw light on his history.
Reference is made to notes on Sinclairs of Dunbeath and Stemster as to younger branches of Dunbeath family. Mr. Alexander Sinclair was of opinion that there was a connection between the Sinclairs of Borlum and Wester-Brims, and the Sinclairs of Brims descended from the Sinclairs of Dunbeath.
A few years ago a family of Sinclairs of Holyhill, in Ireland (of whom notice will be found in "Burke's Peerage"), claiming to be descended from a "Sir James Sinclair of Caithness", made inquiries in regard to their Caithness ancestry. There is no doubt that this family is descended from a clergyman named James Sinclair, rector of Strathbane, a grandson of James Sinclair of Borlum, while the tradition among them that their ancestor was a Sir James Sinclair strengthens the supposition that Borlum was of the Murkle family. John Sinclair of Freswick writes in 1782 from Knaresboro': "At York therse a. very respectable sensible man, Councillor Robert Sinclair of the Holyhill family in Ireland. He has a property there of £400 a year; is marry't here to a lady of good family, by whom he will get £10,000. The late Mr. Pope of Reay knew to what family in Caithness they were connected. He wants to know his descent, when: they emigrate, or when came of the Caithness family".
[NOTE - Subsequent DNA tests have disproved this claim].
In 1853 a letter was received by the late Sir John Sinclair (Barrock) from a gentleman in Ireland to the following effect: "In tracing the pedigree of the Lowry family of the County Tyrone in this country, I find that, early in the 18th century, Robert Lowry, grandfather of the first Lord Belmore, married Miss Sinclair, daughter of the Rev. James Sinclair of Holyhill, County Down, and grand-daughter of Sir James Sinclair of Caithness. Could you assist me in identifying this Sir James, as I am induced, as a matter of family history, to trace this if possible". This no doubt has reference to the family of the Rev. James Sinclair.
JAMES SINCLAIR OF BORLUM had four sons, James, Alexander, William, and Robert, and a daughter, Jean.