The Mahons of Beech Hill, near Loughrea, county Galway, were a branch of the Mahon family of Castlegar. In 1672 Slice, daughter of Thomas Cullen married James Mahon, son of Bryan Mahon. The Beech Hill estate was originally in the possession of the Cullen family. In 1814 Beech Hill was the residence of Bernard Mahon. The estate of James Cullen Mahon at Beech Hill was offered for sale in the Encumbered Estates court in July 1851. At the time of Griffith's Valuation the property was in the possession of Edward Villiers.
- Encumbered Estates’ Court Rentals (O’Brien), Cullen Mahon, 17 July 1851, Vol 10, MRGS 39/004(microfilm copy at NUIG). ; National Archives of Ireland
- Pedigree of Mahon of Loughrea, Oughterclooney, Beech Hill and Castlegar, Co Galway and of Co Tipperary. GO MS 177: 438-451; National Library of Ireland
- Beech Hill. Photographs. 024/068.; Irish Architectural Archive
- Mahon Papers, collection of estate and family records 1690-1957. Collection List 149, MSS 47,791-47,969 & MSS L 199-262 ; National Library of Ireland
Contemporary printed sources
- TAYLOR, George & SKINNER, Andrew. ''Maps of the Roads of Ireland, surveyed in 1777 and corrected down to 1783''. Facsimile of 2nd edition. Shannon: Irish University Press, 1969: 76.
- LEET, Ambrose. ''A directory to the market towns, villages, gentlemen's seats, and other noted places in Ireland''. Dublin: Printed by B. Smith, 1814 : 64
- DUTTON, Hely. ''Statistical and agricultural survey of the county of Galway''. Dublin: Royal Dublin Society, 1824. : 414
- WILSON, William. ''The Post-Chaise Companion or Travellers Directory Through Ireland''. The author: Dublin, 1786 : 120 (Beech Hill)