William Sinclair, 1st Earl of Caithness
William Sinclair (1410–1484), 1st Earl of Caithness (1455–1476), last Jarl of Orkney (1434–1470 [de facto], -1472 [de Jure]), Baron of Roslin was a Norwegian and Scottish nobleman and the builder of Rosslyn Chapel, in Midlothian.
His father Henry, who had been a de facto Jarl of Orkney, died in 1420; William travelled to Copenhagen in 1422 to establish his claim to the Jarldom, but David Menzies was appointed instead, to rule as William's guardian until he came of age. In 1424, William succeeded in wresting de facto control of the earldom from his guardian, but it was not until 1434 that he was acknowledged as Jarl of Orkney by King Eric.
After the death without issue of King Christopher of Norway in 1448, Earl William was mentioned as a possible candidate for the vacant Norwegian throne, Jarl of Orkney was the highest ranking nobleman in Norway, and as such held a senior position in the Norwegian line of succession. However, there are no indications that he pursued this claim.
For a time Henry was protector of the young James Stewart, the later James I of Scotland. He was Lord High Admiral of Scotland, and was Lord Chancellor of Scotland from 1454 to 1456. He became the first Lord St. Clair in Scotland in 1449.
In 1468, King James III married Margaret of Denmark, but her father, the king of Norway-Denmark, was unable to immediately provide a dowry. Instead, he promised that dowry would be provided at a later date, pledging the territory of the Jarldom of Orkney as security for his promise. In 1470, James III offered William the castle and lands of Ravenscraig in Fife, in return for William quitclaiming his rights in Orkney and Shetland, an offer William accepted.
The Norse jarldom technically remained in existence, but William now only had authority over the mainland parts - Caithness and Sutherland. In 1472, it having become clear that the dowry was unlikely to be paid, James declared the Jarldom's territory to be forfeit to the Scottish Crown, to which it was annexed by an Act of the Scottish Parliament, on 20th February. William now wielded his authority under the King of Scotland, rather than of Norway.
Exchanging his inherited lordship of Nithsdale for lands in Caithness, William was granted the hereditary title Earl of Caithness. He resigned the Earldom in favour of his son William in 1476, and lived another 8 years.
He was married three times, first to Lady Elizabeth Douglas, daughter of Archibald Douglas, 4th Earl of Douglas; secondly to Marjory Sutherland, daughter of Alexander Sutherland of Dunbeath, and lastly to Janet Yeman.
By Lady Elizabeth Douglas (c. 1408-1451):
- William Sinclair, 2nd Lord St. Clair (1436) was, in the opinion of the father, a wastrel, wherefore he was disinherited. His family received only the Castle of Ravenscraig in Fife.
- Catherine Sinclair, married Alexander Stewart, Duke of Albany
- (second daughter, name not recorded)
By Marjory Sutherland (married 1456):
- Sir Oliver Sinclair 1452
- William Sinclair, 2nd Earl of Caithness. 1460-1513
- Alexander Sinclair c. 1454
- George Sinclair c. 1453
- Robert Sinclair 1447
- Arthur Sinclair c. 1452
- Eleanor Sinclair, 1457-1518 married John Stewart, 1st Earl of Atholl
- Elizabeth Sinclair, c. 1455-1498, married the Laird of Houston
- Margaret Sinclair, c. 1450 married David Boswell of Balmuto
- Katherine Sinclair 1440-1479
- Susan Sinclair c. 1451
- Marjory Sinclair 1455-80
- Mariota Sinclair c. 1455
- Euphemia Sinclair c. 1470 married John Kincaid Laird of Warriston
- Sir David Sinclair of Sumburgh died 1507
The earl's second son of his second marriage, William Sinclair, 2nd Earl of Caithness, became the designated heir of the Earldom of Caithness and continued that title. The Barony of Roslin went to his first son by that marriage, Sir Oliver Sinclair.
All in all, the Sinclair ancestry is well and thoroughly represented in Scottish and British high nobility, thanks to marriages of his daughters and other descendants. William's daughter of his second marriage, Lady Eleanor Sinclair, married John Stewart, 1st Earl of Atholl, a relative of the kings. Lord Henry Darnley and his son James VI of Scotland descend from Eleanor, and through them, many royal houses of Europe. His other daughter by this marriage, Katherine Sinclair, married Alexander Stewart, 1st Duke of Albany, a nephew of the said Atholl.
- Thomson, William P.L., The New History of Orkney (Edinburgh, 2008) p 174-179
- Hamre, Lars, Norsk historie frå omlag år 1400 (Oslo, 1968) p 128
- Ravenscraig Castle
- Balfour Paul,vol ii, pp333-336
- Thomson, William P.L., History of Orkney (Edinburgh, 1987) p 134-136
- Charles Mosley, Burke's Peerage and Baronetage, 107th edition.
- Sir James Balfour Paul, The Scots Peerage : founded on Wood's ed. of Sir Robert Douglas's Peerage of Scotland; containing an historical and genealogical account of the nobility of that kingdom. Edinburgh 1904. 
|Peerage of Scotland|
|Jarl of Orkney
– 1472 (seizure)
Territory seized by Scotland
|Earl of Caithness
George Crichton, 1st Earl of Caithness
|Lord High Admiral of Scotland||Succeeded by
David Lindsay, 5th Earl of Crawford
William Crichton, 1st Lord Crichton
|Lord Chancellor of Scotland
Andrew Stewart, 1st Lord Avandale