Cavan was accepted by CDSNA as a sept in December 1988 based on its being noted as a sept in the 1954 publication Badges of the Scottish Clans. This sept name has a strong connection with Agnew above.
The research for this sept name was taken from a single source: Kevans DNA project (hosted by worldfamilies.net) @ http://www.worldfamilies.net/surnames/kevan/mtdna. The editor of this article did such a wonderful job of documenting that no effort is given to re-invent his/her wheel. Some of this will be seen to be a repeat of the text for Agnew.
The surname Kevan is native to Galloway and thought to be derived “from the land of Cavens in the parish of Kirkbean, Kirkcudbrightshire. (George F. Black, The Surnames of Scotland: their Origin, Meaning & History, p. 143; John E. Wilson, Gazeteer of Scotland, p. 84] Cavens, which, lies a few hundred yards south of the village of Kirkbean, with land running South and Eastward down to the banks of the Nith estuary, and was once part of the Earldom of Morton, was associated with the Maxwell family as early as the 15th century. (See the Maxwell Society website)
JAMES MAXWELL, the third son of John Maxwell, Master of Maxwell, who was killed at the battle of Lochmaben, 1484 (see title Nithsdale), is said to have been the ancestor of the Maxwells of Cavens.1 Who his immediate successors were has not been ascertained, but the next possessor of the estate on record is
Herbert Maxwell, of Cavens, who died 24 March 1572-73, leaving two sons:
2. John, who, with his son Joke, is named in Herbert's will as his “oyes”
(James Balfour Paul, The Scots Peerage, p. 126; P. H. M’Kerlie, History of the lands & their owners in Galloway p. 162)
Cavens came into Maxwell possession when John Maxwell, 7th Lord Maxwell and grandson of the third Earl, briefly claimed the Earldom after the 4th Earl was executed for involvement in the murder of Lord Darnley, and [b]y 1589, Cavens [wa]s in the hands of Herbert Maxwell of Cavens who was tried for the murder of Sir Robert Maxwell of Dinwiddie in 1605. John Maxwell, Bishop of Ross was a scion of Cavens Maxwells as were the Maxwells of Kirkhouse. The Cavens Maxwells died out in 1640 and the cadet line of Maxwell of Kirkhouse inherited. James Maxwell, Earl of Dirleton was the last of that line and the property then appears to have been inherited by members of the Murrey family, Earls of Annandale. An eighteenth century house possibly a house built for William Maxwell of Preston is the main caput, is now the Cavens Country House Hotel. (from the Maxwell Society)
M. Kerlie’s History mentions a William Maxwell, son of William Maxwell of Cavens, parish of Kirkbean, who had retour of the farm of Gate side on the 15th April 1617 [ p. 18]
The earliest example found thus far of Cavens used as a surname dates to the late 14th or early 15th century. Gilbert de Cavens, who died in 1420 and for a brief time was Bishop Elect of Galloway, held a Bachelors degree in Canon Law by 1406 and was a long-time servant and cleric for the Douglas family, acting as “chaplain and familiar” of Margaret Stewart, Countess of Douglas in 1406 and tutor for her eldest son Archibald Douglas.
The name Kevans or Kavands is also found as a place name in Wigtownshire from at least the 15th century:
The first lands obtained in the parish of Sorby by the Agnews of Lochnaw were the farms which had been given for the support of the church at Cruggleton, and called the church lands; viz., Baltier, Cults, and Kevands. The grant was subsequent to the Reformation, and by charter in January 1581 by King James VI. Kevands is stated to have been bestowed in 1421 by Archibald, Earl of Douglas, to a John de Cavens, [PH M'Kerlie, History of the lands & their owners in Galloway p. 350]
A later addendum by M’Kerlie, however, argues that Balter, Cults, and Kevands could not have been accepted by William Douglas of Leswalt as an equivalent for Lochnaw when he gave up the castle, etc.[because] “they had [already] been appropriated or set apart for the support of the Church of Cruggleton.” [Furthermore] search has recently been made in vain for any charter under the Great Seal in confirmation of such a grant to William Douglas. There were two charters granted by Margaret, Countess of Douglas, and confirmed by King James I., but they did not refer to any portion of the Cruggleton property. [M’Kerlie, p. 338]
Sir Andrew Agnew, however, in The Agnews of Lochnaw: a history of the hereditary sheriffs of Galloway, p. 242, says that “the Sheriff simultaneously increased his Galloway estates and acquired the lands of Cults, including Baltier and Kevands”. The deed conveying these lands to the Sheriff from his son-in-law, James Kennedy, was signed at Lochnaw "in presence of Quentin Agnew, lawful son of the said Sir Andrew Agnew;" and among the charters which then came into his possession, as evidents, is a curious one by the Earl of Douglas to John de Cavens, dated 1421 showing the origin of the word Kevands, which, though much altered by modern orthography, is always pronounced Cavens.
According to Sir Andrew, the “first rentalls of the lands of Cruggleton Cavens” brought in “300 marks.” [Ibid., p. 329]
The Kevans of Galloway. Article on the World Families server @ http://www.worldfamilies.net/surnames/kevan/mtdna