Brownlee was accepted by CDSNA as a sept in July 1985 as a variant of Brown.
From the website, The House of Brownlee, a brief article is given explaining the origins of the name Brownlee.
“Brownlee and Forest are common names between Garrion and Carstairs, both of which adjoin Carnwath in Lanarkshire although the origin of Brownlee may be debated, there appears to be enough evidence to warrant an assumption that the earliest recorded Brownlees either took the name from the LEE property or from the estate called Brownlee which lies between Garrion Bridge and Law and was originally the Barony of Mauldslie. In a letter to Allan Lindsay Arnold Brownlee, Sir James Montieth-Grant, Lord Lyon King of Arms on 5th September 1969, stated: “The cinquefoil ermine alludes to Hamilton, who were portioners of Brounlie in the Parish of carluke in the 17th century. The name Brownlee is said to have originated from this estate.”
The lands of Carnwath have also been associated with the Summerville, Dalzell (as earls of Carnwath) and Lockhart families but probably originated within the Douglas family. Dalzell and Lockhart are families with close ties to Douglas. In a genforum post by Peter Sommerville titled Re: de Sommerville / Carnwath Castle lineage it was stated:
In 1317 Sir John Somerville married Lady Elizabeth Douglas and part of the dowry was a castle just outside Carnwath, called Cowthally. It had recently been burned down and the part that was left was just one square stone tower. Over the next two hundred years many additions and improvements were made and the castle was the main family home of many generations of Lord Somerville.
Another possibility for the name Brownlee comes from the French name Le Brun who used the French lily, the Fleur de Le, in their arms as relatives of the French King and were sometimes described as Brun o’ le.
Although claimed as a sept of Douglas, the Brownlees of Australia and New Zealand claim to have never been a sept of any family until the early 1980s. The Brownlees’ choice to become a sept of Hamilton is based upon information found online: The Brownlees Were Never a Clan.
Prior to 1969, Allan Lindsay Arnold Brownlee (Lindsay) wrote to the Court of The Lord Lyon in Scotland seeking information whether the Brownlees were ever organised as a clan. He was advised in a letter from the Lyon Clerk and Keeper of the Records that no evidence could be found which would indicate that the Brownlees ever had an established clan structure. Because of the long association with the Hamilton clan, as evidenced by feudal tenure of Hamilton lands dating back to 1547, the Lyon Court made a recommendation. He said "If enough evidence could be gathered indicating that a large number of Brownlees wished to become dependents of the Duke of Hamilton, a suitably phrased letter to the Duke of Hamilton, might persuade him to regard the Brownlee family as dependents of the House of Hamilton".
After consultation with quite a number of Australian Brownlee / Brownlie families and meeting many of the New Zealand families, Lindsay forwarded the following letter to the Duke of Hamilton:
"Baldovan Park"Strathbogie 3666,Victoria, Australia17th September, 1981Angus Alan Douglas Douglas-Hamilton,M.A.,A.F.B.I.S.His Grace the Duke of Hamilton and Brandon,"Lennox Love",Haddington, East Lothian,Scotland, U.K.Your Grace,In a letter from the Lord Lyon to me in 1969 he suggested that I might approach Your Grace, as Head of the House of Hamilton, with a submission that you consider a proposal that people of Scottish origin named Brownlee/Brownlie be adopted as “dependants” of the House of Hamilton, and with this object, I now submit this petition. As background to this I should indicate why it devolves upon the undersigned to prepare and forward this submission.In 1969 the Lyon Court accepted my petition for a grant of arms, and subsequently other members of this family have matriculated. In addition, I have been most active in holding this and other Brownlee families together. In 1969 I privately circulated a book “THE BROWNLEE FAMILY” (a copy of which I have enclosed for reference). This was printed after nearly 20 years research in many parts of the world.I am the second son of a second son. My grandfather, David, and his wife came from Forfar. Further details are set out on page 49 (see enclosed book). I have had a lifetime interest in Genealogy as a hobby, and served 16 years as a Councillor of the Genealogical Society of Victoria and recently retired from the Presidency after 9 years in the chair. I am a Fellow of that Society and Honorary Life Member. I have also been a member of the Scottish Genealogy Society for 14 years, and a Vice-President of the Heraldry Society (Australian Branch).In the course of my research into the Brownlee origins, and subsequent to the production of the book, I have been in communication with people of the name in Canada, America, Scotland, New Zealand, Australia and even a few in South Africa (estimated total Brownlees/Brownlies in those areas approximately 5000), and in January last, my wife and I were guests at a big gathering of Brownlees in the North Island of New Zealand, where I was asked to promote action to establish an international Family Society. From Australia also I have support for this suggestion - all of which has encouraged me to proceed with this plea.In the name of the Australian and New Zealand Brownlees, I therefore formally seek Your Grace’s patronage as Head of the House of Hamilton, by accepting our tribute as Liege dependants of the House of Hamilton.Yours sincerely,Allan Lindsay Arnold Brownlee
"I have spoken to the Lord Lyon and, with the benefit of his advice, am happy to agree to your request and grant my patronage to the Australian and New Zealand Brownlees."(He went on to say), "You will be most welcome to come and visit us at Lennoxlove if you come to Scotland."J I D Pottinger, Lyon Clerk and Keeper of the Records for the Court of the Lord Lyon, also acknowledged this in a letter dated 23 November 1981. He advised "I have today attached these letters to your (Allan Lindsay Arnold Brownlee) Process, which comprises the bound-up papers of your Petition for and Grant of arms in 1969-70, where they will remain on permanent record."
The connection between the Hamilton’s and the Douglases is a strong one and the sharing of Brownlee as a sept is another link in the chain.
The Brownlees Were Never a Clan. http://www.brownlee.com.au/Pages/Heraldry/Brownlee-never-clan.html
The House of Brownlee. http://www.brownlee.com.au/Pages/Origin-of-the-Name.html