Early recordings..

The Slys have farmed land for many centuries. Their stronghold was, appropriately enough, in the valley of the Wily. The earliest date of their appearance is uncertain but they were situated as Yeoman in the Wily Valley before the days of Queen Elizabeth and remained as such after the time of Queen Victoria. They were at Corton before 1300.
The early records of Wiltshire contain many names such as Walter de la Sley, who lived in the Hundred of Klan( Calne) in 1265 and Huge de la Sle, who was of Warminster in 1273, and there were Slykes just over the border both in Hampshire and Dorset.
In 1360
Henry Sleye is recorded of Fyntngton.
In 1412
John Sly is mentioned as holding lands in Lytecote for life.
In 1421
There is a William Slegge of Salisbury Co.Wilts.
In 1553
Boyton Church goods received for the King's use were delivered to Thomas Harvey and John Slye.
In 1560
The earliest parish register of Boyton, a village situated on the Wily, between Wylye and Warminster, contain entries relating to the Slys and in
1596
A measuage and 48 acres of land, 6 acres of meadow,1 1/2 acres of pasture and pasture for 140 sheep in Corton, was granted by Edward Lambert at Boyton-cum-Corton , to hold for the lives of George, George and John Slis, they paying 26/- a year therefore. George Slie senior died at Corton on December 1st,1605 and on the 6th of May,1634 Elizabeth ( his widow) died, and on that day George Slie Junior entered into possession.
In 1600
The 6th day of September was buried Stephen Bennet, servant to John Tilley and George Sly.
In the Bayton Register duly appears the entry.
In 1605 George Sly was buried the first day of December.
Despite the troubles that afflicted George Sly the second later in life, that he was particularly well educated for his time may be inferred from the fact that-
In 1611
" He signs the register as Churchwarden in excellent handwriting".
in 1613
Edith the daughter of Drewe Sly and Jean his wife was baptised at Boyton.
The registers at Boyton are of much interest as indicating a possible line of research for Shakespearean students.
It may however be remarked that though there were several families of the name in the parish at the outbreak of the Civil War, the registers have no entries regarding male members of the family after 1642 and perhaps military affairs may have occupied their attention from that time. There were certainly troubles in the parish for two successive Rectors were sequestered. The earlier entries spell the name Sly, but for a portion of the 17th century most of the entries are in the form of Slye.
In 1642
Under date of July 28th, and with reference to the Assizes at Wells, there is a letter from William, Marquis of Hereford to Sir Robert Foster, judge of the western Assizes- " The bearer John Slye whom I find very affectionate to the King's Service,fell into a misfortune April last was twelve months for which his desire is to press his this Assizes and not be bound over to the next. I pray you afford him all the lawful favour you may".
This may not refer to a member of the Boyton family but, on the other hand, the Somersetshire border is quite close and probably this John Slye had some connections with the family in the Wily Valley, which is in the western Assizes area.
In 1667
The last entry of the name in the Boyton register appears recording the burial of Elizabeth Sly,widow.
In 1662
The Rector of Upton Level, a neighbouring village, is given as Edmund Slyrton. Can this be Edmund Sly of Corton ? for we find
In 1670
Edmund Sly,Rector of Sherrington, a village joining Boyton to the South and then living in the gift of the Lords of the Manor of Boyton who were at this time the Lamberts. Lamberts originally of Kerton Holland in Lincolnshire, another stronghold of the Slys.
Probably Edmund Sly held the living of Sherrington as well as Upton Level for
In 1677
Under the date of July 12th Dr Lancelot Addison writing to Williamson says " I am just now advised that by the death of a Mr Slye, a prebend will be vacant at Sarum and a parsonage called Level's Upton. etc"
In 1728
The family make their first appearnce in the registers of the Parish Church of Warminster, a few miles away.
In 1797
Thomas Sly was one of the original Warminster band of Volunteer Soldiers formed in those troubled times for the local defence against a Napoleonic invasion or other national emergency. The quaint rules of conduct for the soldiers are mentioned in Daniell's " History of Warminster".
The family was represented in Warminster by freeholders farming in the neighbourhood till recent years. Families of the name at Devizes and Salisbury were related to the Warminster Slys and the Yeoman tradition of active participation in parochial affairs was maintained;the last representative in Warminster taking his turn in the chair at the local Council and the founder of the family in Salisbury becoming a Trustee of the City Charities. In more recent years the family interest extended to Imperial affairs, where they were represented by Sir Frank Sly, a distinguished Indian Civil Servant.

The above are extracts taken from a paper by Martin Sly between 1918-1930 and I must thank James Finday Sleigh for passing all the information to me.