In 1632 the Ruthin Castle Estate was purchased from the Crown by Sir Thomas Myddelton of Chirk Castle (1585-1666), who acquired the stewardship of the lordship in 1635. He was MP for Denbighshire from 1625, was elected for the Long Parliament and became a Parliamentary commander during the Civil War.
Sir William Myddelton (1694-1718), 4th baronet, a copy of whose will is in this archive (ref: DD/RC/1164) died unmarried and the baronetcy became extinct. The Chirk Castle Estate, with the lordships of Chirk, Chirklands and Ruthin passed to Robert, younger son of Richard Myddelton of Llysfasi by his wife Elizabeth Ryder. Robert died without heirs in 1733 and was succeeded by his brother, John (d. 1747). John's son Richard and then his son of the same name can be found on mortgages of the Ruthin estate and other property from the 1750s onwards.
On the death of John's grandson, Richard Myddelton of Chirk Castle, the last surviving male heir of the Myddelton family in 1796, the estate was divided between his sisters Charlotte, Maria and step-sister Harriet. Charlotte and Maria were the daughters of Elizabeth (nee Rushout, d. 1772), sister of Lord Northwick, and Harriet the daughter of Mary, formerly Mary Lloyd of Rhydwriel (d. 1788). The original division was disputed resulting in an Act of Parliament dated 1819 which was directed by the High Court of Chancery. The Chirk Castle Estate passed to the eldest sister, Charlotte, wife of Robert Biddulph of Ledbury, Herefordshire, who prefixed his surname with Myddelton. Maria (d. 1843), who had married Frederick West (d. 1852) third son of John, Earl De La Warr in 1798 inherited the lands later known as the Llanarmon Dyffryn Ceiriog Estate after the division. The Ruthin Castle Estate passed to Harriet who did not marry and who bequeathed the estate to Maria's family on her death in 1848. The Wests lived at Culham Court, Berkshire and their eldest son Frederick Richard West at Arnewood House near Lymington before the family moved to Ruthin after the death of his aunt Harriet. Frederick West and Maria had already expanded the Ruthin Castle Estate by purchasing property in Castle Street, Ruthin in 1827.
Also in 1827 Frederick Richard West had married Theresa John Cornwallis Whitby the daughter and only child of Mary Anna Whitby, the heiress of Admiral William Cornwallis of Newlands. He therefore inherited both the Ruthin and Llanarmon Dyffryn Ceiriog Estates and acquired Newlands Manor Estate in the parish of Milford by marriage. His eldest son, Frederick Myddelton West died unmarried without heirs in 1868, outliving his father by only six years and was succeeded by his brother, William Cornwallis-West. In what is practically the only item of personal correspondence preserved in the archive (Ref DD/RC/1073) there is reference to Frederick Myddelton West's drinking and debts. There had already been some sales of property in the Myddeltons' Chirklands estates in the 1850s and 60s to repay some of them.
Frederick Richard West and his son William Cornwallis West developed existing sites in Ruthin and purchased others, and embarked on a building programme which included cottages and public houses. William also attempted to develop land on the Newlands Estate bordering the sea at Milford and renaming it Milford on Sea. The family also had industrial interests in mining and quarrying at Llanymynech, Ruabon and Wrexham. A sidelight on the influence of the Myddelton/ West; Cornwallis West family on Ruthin can be seen in the small section concerning the internal rearrangement of the parish church in the 1860s.
From 1859 the estates were subject to a settlement, the settled estate's main trustees being solicitors and agents Longueville and Williams of Oswestry. A further settlement of the estate was made when William's only son George attained his majority in 1895. Both William's daughters made famous marriages, Constance married Hugh Grosvenor, second Duke of Westminster, and Daisy (Mary Theresa Olivia) married Heinrich, Prince of Pless who took a lease of Ruthin Castle in 1911. The estates had been mortgaged by the time of George's inheritance and became progressively more so. He was a well-known figure in Edwardian society, was the second husband of Lady Randolph Churchill and later married the actress Mrs Patrick Cambell. He was declared bankrupt soon after his father's death in 1917. Unfortunately material reflecting the social milieu the family occupied and the extravagant spending in which they reputedly indulged is not reflected directly in the collection. The Ruthin, Llanarmon and Newlands Estates had all been sold by 1920. George Cornwallis West died by his own hand in 1951 having suffered for many years from Parkinson's disease.
The collection includes estate and family papers. The organisation of the collection reflects the complex nature of the estate's development.