From16th century Perthshire Clanlauren genealogies (that would withstand judicial review) is that the surname McLaren / McLaurin or similar, originated in western Argyll and later in different decades as they migrated to Perthshire among an extremely large cluster of 'Loarn origin Scots' whose YDNA is closely related. We could just as easily been named Robertson, Paterson, MacVicar, McCallum (esp. in Argyll), McArthur and many others, simply luck of the draw at a certain point typically in the 17th century.
Lorin Mak Gilserf in 1258 the same as Lorne Mach gilherve in 1266
“The Surnames of Scotland” Black
Lorn de Ardebethy, 1296 equals Laurin of Ardveich, according to many, many authors transcribing the Ragman Roll of 1296. Whether he is actually a McLaurin is another question entirely.
Johannes de Larin Dominus Ergadie, 1340 is John Stewart of Innermeath Lord Lorn I, “Bishops of Argyll” Turner
“The name Laurin seems identical with Lorn, or derived from the same root; and that root is said to be ‘Laurence’.”
Daniel MacLaurin, History in Memoriam of the Clan Laurin, page 14, 1865,
“This ancient patronymic evidently derived from the Dalriadic chief Laurin of Laurin, in Argyle,”
George Fraser Black, “The Surnames of Scotland” page 534, 1946,
“Chief of the tribe of Laurin in Argyll”
Margaret MacLaren, “The MacLarens” page 9, 1960.
“Yes, it seems obvious to me that the spelling MacLaurin arose from the Gaelic pronunciation MACHD-LA-OO-RIN” Ronnie Black 26/3/2106
“it is an ancient Argyll name!”
Brigadier John MacFarlane, the last native speaker of the Lorn dialect of Argyll Gaelic. “The Newsletter of An Comunn Gàidhealach Ameireaganach”, President, “The 1745 Association”, 2018
“Loarn is an old Gaelic name. In the Book of Ballymote  there is for instance a Loarn who become Loernus in Adamnan's Latin.” Dr. D.C. McWhannell, 2018
In “Manuscript 1467” written by Dubhghall Albanach mac mhic Cathail (‘Scottish Dugald son of the son of Cathal’), there are four lineages with names of what scholars over the decades have thought to be Laurin or Laren.
The Clann Ghille Eadhráin (MacLeran) lineage lists “mhic Lamrainn”, which is “son of Laurence”.
The MacLabhartaigh (McLaverty) was mistaken for “McLaren” by W. F. Skene. This lineage contains “mhic ab----?----” which Skene took to mean “The Abbot of Achtus”, which became “Abbot Labhran of Achtow” the patronym of the modern MacLaren Clan, so that is a fictional character created by Skene, since these are all West Argyll lieneages in Manuscript 1467.
The Mac Gille Ainnrias (Gillanders) lineage lists “mhic Loairn”, which is “son of Loarn”
The Mac an Aba Uaine (“the son of the Green Abbot’) lineage lists “mhic Loairn”, which is “son of Loarn”
“What this appears to indicate is a "flexibilty" on the part of scribes transcribing the name of even a famous individual.” Dr. D.C. McWhannell, 2018
Dr. D.C. McWhannell writes
“This reply may seem somewhat gnomic however I should like to draw your attention to the following information since all these entries refer to one man who was Laurencius or Laurentius in church Latin, Labhras in some Irish texts and who was probably originally baptised as Lorcan. He was Archbishop of Dublin at the time of the Norman invasion of Ireland. [October, 1171]
1. sanctus Laurencius O Tuathail arciepiscopus
2. Labhras h- Tuathail, archdeaspog Atha Cliath & Laighean
3. Lorcan Ua Tuathail .i. Labhras airdespoc Laighen & lrgatt na h-Ereann
What this appears to indicate is a "flexibilty" on the part of scribes transcribing the name of even a famous individual.
Labhrunn seems to be a "new" name adopted when the cult of St.Laurentious (St. Laurent) spread west to Ireland and north to Scotland with the Normans.
The names of foreign persons particularly internationally famous saints like St.Laurentius were converted from Latin into many other Languages i.e Lorenzo (Italian), Laurent (French), Lawrence (English), Laureins (Flemish), Labhras (Irish) and Labhrann (Gealic) and were adopted as baptismal names either because the saint was revered by the family or because the male child in question was born on the saints day (Lawrence's feast day is the 10th. of August).”
Dr. McWhannell continues
“Some information and thoughts
The Dál Riata Foundation Myth (perhaps somewhat challenged by archaeology)
In the 6th century, Irish migrants crossed the straits of Moyle (The North Channel) invading Lorn and the coast to its south, as well as the islands between there and Moyle in Ulster, establishing the Gaelic kingdom of Dál Riata. In around AD 500, Loarn mac Eirc (a brother of Fergus Mór) became king of Dál Riata, founding the Cenél Loairn. Gradually Dál Riata came to be split between a small number of kin groups, of which the Cenél Loairn controlled Mull and what is now Lorn; the realm of the Cenél Loairn (including Mull) acquired the name Lorn in reference to them.
(1) Loarn was one of the three sons of Erc who founded the kingdom of Dál Riada in Argyll in the 5th century; the genealogies of many Scottish Highland families were traced back to him as an ultimate ancestor.
(2) Larne takes its name from Latharna, a Gaelic territory or túath that was part of the Ulaid minor-kingdom of Dál nAraidi. The name spelt as Latharne was used at one point in reference to the Anglo-Norman cantred of Carrickfergus. Latharna itself means "descendants of Lathar" The area where the modern town sits was known in Irish as Inbhear an Latharna ("rivermouth of Latharna") and was later anglicised as Inver Larne or simply Inver. The territorial name Latharna was only applied exclusively to the location of the present town in recent centuries.
(3) Lathar was a daughter of Úgaine Mór, a High King of Ireland during pre-Christian times. Ugaine reputedly gave Lathar a stretch of land along the coast of County Antrim, from Glenarm to the Inver; which would one day make Larne.
Laurentius is a Latin given name that means "From Laurentum" (a city near Rome).
The name became widespread due to the fame/cult of St Laurentius one of the most widely venerated saints.
Early modern Irish for Laurentius is Labhrás
From Latin Laurentius. The given name appears to have been introduced to ireland by the Normans,
Laurence Bishop of Argyll and the Isles
Elected bishop of Argyll succeeded Alan (d. 1262), his consecration taking place after 31 March 1264. He appears as bishop on 20 June 1268 and again on 29 October 1299. He was a Dominican Friars Preacher before his election, and may have been a member of the MacDougall family of Argyll. He left Scotland in October 1273, with four other Scottish bishops, to attend the general council at Lyons, returning after July 1274. He was dead by 18 December 1300.
Assuming Lawrence was a MacDougall and of legitimate descent then he would have had a Scandinavian Y-Chromosome probably R1a M420.
Laurentius/Laurencius would have been Labhras in Early Modern Irish.
The Gaelic dialects on both sides of the North Channel are now extinct though native speakers were still to be found on the Mull of Kintyre, Rathlin and in North East Ireland as late as the mid-20th century. Records of their speech show that Irish and Scottish Gaelic existed in a dialect chain with no clear language boundary. This dialect will probably have been close to Middle Irish (sometimes called Middle Gaelic) which was spoken in Ireland, most of Scotland and the Isle of Man from the 10th to 12th centuries.
In Macbain’s Etymology of Gaelic  a date for the use of Labhran in Scotland is given as 1467.
“Laurence, G. Labhruinn, M.G. Labhras (1467). Ir. Laurint (Saint), from Lat. Laurentius, St laurence, the ultimate stem being that of lat. Lauras, a laurel. Hence M’Labhruinn, or Mac-laren”
In ms 1467 it is in the genitive “mhic Lamrainn”. Should the m be lenited then it be can be sounded as v or w depending on the dialect and/or the position of the lenited m. This ms 1467 rendering may thus be considered equivalent to “mhic Labhrainn” and hence the father was named “Labhran”.
It is clear that the given name Labhran had arrived in Argyll by the time of Bishop Laurentius’ birth circa 1224 while the name had been in use in Ireland (Labhrás) since around 1180 and in Scotland (Labhran) since around 1200.
The seemingly earliest extant individual sloinneadh (a designation, patronymic and explanation of kinship) in Argyll gives Vicar Dubghall as a grandson of a Labhrunn (cognate with Labhrann/Labhran)
So we have Dubhgall son of Gille Chriost, grandson (or descendent) of Labhrunn. Assuming Dubhgall was born circa 1400 and using 30 years a generation gives Gille Chriost as b. circa 1370 and Labhrunn b. circa 1340. The dates 1340, 1370 and 1400 when the birth of the future clergyman occurred are consistent with the period for the formation of surnames.
The kindred of Labhrunn is not indicated however if this clergyman had male issue they might well have acquired the surname MacLabhruinn thus recalling their descent from a well known and probably respected clergyman.”
Copyright D.C.McW 3rd.January 2018