I found this interesting as it explains the line of "ownership" of Cumnock.
THE ARMS OF THE BARONIAL AND POLICE BURGHS OF SCOTLAND BY JOHN, MARQUESS OF BUTE, K.T.
J. H. STEVENSON AND H. W. LONSDALE, EDINBURGH. WILLIAM BLACKWOOD & SONS 1903.
UNIFORM WITH THIS VOLUME. THE ARMS OF THE ROYAL AND PARLIAMENTARY BURGHS OF SCOTLAND.
BY JOHN, MARQUESS OF BUTE, K.T., J. R. N. MACPHAIL, AND H. W. LONSDALE.
A Cross Calvary. Cumnock. pp148/151
This is the same device as that which forms the blazon of Kinross, and for the same reason — viz., that the Town Cross is the principal monument of antiquity in the burgh. We call it a cross because it is so called by the town clerk as well as in general parlance; but it has, as a matter of fact, been decapitated, and had a stone ball substituted for the cross proper, in which condition it is represented upon the town seal. The actual structure is also raised upon five steps (perhaps symbolical of the wounds of Christ), and is so represented upon the seal; but we adhere in the illustration to the three steps regarded as symbolical of Faith, Hope, and Charity, leading up to Christ, and which are identified with the cross Calvary of heraldry.
Cumnock, which became a Police burgh in 1866, was created a burgh of barony by James IV., September 27, 1509 (Reg. Mag. Sig., sub die), and the King expressly states that he did so as a favour to James Dunbar of Cumnock. On the creation of the regality of Cumnock on October 18, 1680, in favour of Charles, Lord Crichton, Cumnock was made a free burgh of regality with the usual privileges. These Dunbars were of the family of the Dunbars, Earls of March, and bore, like them, gules, a lion rampant argent within a bordure of the last, charged with eight roses of the first, quartering Randolph, Earl of Moray, or, three cushions pendent within a double tressure flory-counterflory gules, as heirs of Agnes Randolph, Countess of Dunbar and
March by marriage, and of Moray in her own right. In allusion to this family the present writer suggested, in dealing with the municipal arms of the Royal Burgh of Dunbar, that that Burgh might have borne argent, a castle gules within a bordure of the last, charged with eight roses of the field; but in this case it would be possible to act upon the same idea without reversing the tinctures, and to read, Gules, a cross Calvary argent, within a bordure of the last, charged with eight roses of the first.
Note. — The present writer has been in the habit of mentioning in connection with each burgh those cases in which they have given a title to a peerage, and, in order not to depart from this rule, may say that while he is Lord Crichton of Sanquhar from January 29, 1487-88, he holds also the title of Lord Crichton and Cumnock from June 12, 1633, and that he is a representative of the Dunbars of Cumnock and Mochrum, as well as of the main stock of the Dunbars, Earls of Dunbar and March. David Dunbar, on the resignation of his father, George, Earl of Dunbar and March, received a charter of the barony of Cumnock in 1374-75. His line ended in three co-heiresses, Euphemia, Margaret, and Janet, which last married Patrick Dunbar of Kilconquhar. This Patrick was the only son and heir of George Dunbar, attainted Earl of Dunbar and March, who enjoyed
Kilconquhar because Kilconquhar was held from the Church of St Andrews, and therefore remained to the family when all the rest of their property, being a fee from the Crown, was forfeited at the attainder. His investiture with her in the half of the barony of Mochrum is dated April 3, 1479. Their descendant, Andrew
Dunbar of Kilconquhar, died childless in 1564, whereupon the estate devolved upon his sisters Janet, Alison, Elizabeth, and Margaret as co-heiresses. Margaret married William Macdowall of Dowaltoun, and was mother of John Macdowall, who married Mary Macdowall, heiress of Freugh ; and their ultimate heir, John Macdowall of Freugh, married the Lady Elizabeth Crichton Dalrymple, eldest daughter of Penelope, Countess of Dumfries in her own right. They had issue Patrick Macdowall of Freugh, who succeeded his uncle as fifth Earl of Dumfries in 1768. He was the great-grandfather of the present writer. He sold Freugh, while retaining Cumnock and Mochrum, and dropped entirely the name and arms not only of Dunbar but also of Macdowall, taking the name of Crichton only.
'There is, however, over the door of the dovecot at Dumfries House a badly executed stone carving of the arms of Macdowall of Freugh. The dovecot is older than the period of Earl Patrick's acquisition, and the panel has every appearance of having been inserted. The probable inference is that, when he sold Freugh, he removed from it this panel of his family arms.
www.archive.org/stream/armsof...erich_djvu.txt 
