Henry Cannon bought the village of Kilmaine, county Mayo, and surrounding townlands from the Millers of Milford, parish of Kilmainemore, in the early 19th century. By the time of the first Ordnance Survey the Cannon estate was held by John Fair, executor to his brother-in-law, Henry Cannon. An estate of 1650 acres in the vicinity of Kilmaine, some of it church land, was advertised for sale by John Fair in the Encumbered Estates' Court in 1852, John William Cannon was the petitioner for the sale. At the time of Griffith's Valuation John E.Cannon owned eleven townlands in the parish of Kilmainemore. In the early 1850s John William Cannon bought the Castlegrove estate in the parish of Kilbennan, barony of Dunmore, county Galway, from the Blakes. Lane indicates that this family also purchased part of the St. George's Urracly estate in 1853. In 1876 John William Cannon of Castlegrove, county Galway, owned 994 acres in county Mayo and 4979 in county Galway. Bateman records " W.J. Cannon" as the owner of a total estate of 5973 acres in counties Galway and Mayo in 1883.
- Milford Papers, contact John Ormsby, Milford, Kilmaine, county Mayo; Private Possession
- Encumbered Estates' Court Rentals (O'Brien), Fair, 6 Oct 1852, Vol 18, MRGS 39/008, (microfilm copy in NUIG); National Archives of Ireland
- Castlegrove photos. 054/020 & 030/056; Irish Architectural Archive
Contemporary printed sources
- PARLIAMENTARY PAPERS. ''Return of owners of land of one acre and upwards, in the several counties .... in Ireland''. HC 1876, LXXX: 308
- HUSSEY DE BURGH, U. H. ''The Landowners of Ireland. An alphabetical list of the owners of estates of 500 acres or £500 valuation and upwards in Ireland''. Dublin: Hodges, Foster and Figgis, 1878. [available online at www.askaboutireland.ie] : 70
- ''GRIFFITH'S VALUATION OF IRELAND'[Primary Valuation of Tenements]', 1850-1858. : Tuam Union, 143
- PARLIAMENTARY PAPERS. ''Return of names of proprietors and area and valuation of properties in counties in Ireland, held in fee or perpetuity or long leases at chief rents,'' 1876. (412) LXXX. 395: 148.
- BATEMAN, John. ''The great landowners of Great Britain and Ireland''. London: Harrison, 1883. : p.76
Modern printed sources
- LYONS, Mary C. ''Illustrated Incumbered Estates, Ireland, 1850-1905.'' Whitegate, county Clare: Ballinakella Press, 1993. : 42-43
- BLAKE, Tarquin. ''Abandoned mansions of Ireland''. Cork: Collins Press, 2010.: 110-117 (Castlegrove)
- ''Jnl. of the Galway Archaeological and Historical Society'': LANE, Padraig G. Purchasers of land in counties Galway and Mayo in the Encumbered Estates court, 1849-1858. XLIII (1991), p. 103