Flesk Castle, Killarney dates to circa 1809. Its origins are associated with the Coltsmann family, butter merchants of Northumberland stock, who established themselves in Kerry as landlords. Its construction is attributed to John Coltsmann junior Esq, the only son of John Coltsmann Esq of London and Killarney. His achievement was described in an obituary composed on his early death on 15 January 1849, at age 54:
Mr Coltsmann was a highly accomplished gentleman and when a young man was universally admired in these counties and on the continent for his singular beauty. Familiar with all the arts, he designed and saw executed the picturesque Castle popularly called by his name and which, coupled with the magnificent landscape it commands, presents a feature of striking interest to the tourist.
John Coltsmann junior Esq was interred in the family vault at Muckross Abbey with his parents, John and Christina Coltsmann, and his sister, Christina. He left no issue, and his estate devolved to his nephew, Daniel Cronin junior Esq.
Numbered among the Cronin-Coltsmann holdings was Coolcurtoga, a townland in the parish of Killaha. The following account relates to this period of landlordism and has been prepared by Mary O’Donoghue of Coolcurtoga, the author of ‘Coolcurtoga: A Story of Ireland.’
Coolcurtoga in the Land War
How many people can say that the house they are living in was the scene of a Land War eviction. I live in such a family home. The tenant farmer here, Daniel Casey, and his wife Johanna Riordan, and their six daughters were evicted.
The bailiffs and constabulary were sent by Messrs Hussey and Townsend from Tralee on 29 April 1892. They were acting on behalf of the landlord, Daniel Cronin-Coltsman of Flesk Castle, Drumhumper, Killarney.
Coolcurtoga House was built in 1877. The younger Casey daughters would have been born here. A number of older pre-famine house ruins are in the vicinity. Their tenants were included in the tithes register of 1833.
Daniel Cronin Esq of The Park, Killarney was the original landlord of Coolcurtoga during the tithes period. His mother was a sister to John Coltsmann Esq of Flesk Castle. John Coltsmann willed his estate to his nephew, Daniel Cronin, with the stipulation that he take the name Coltsman. So came about the name Daniel Cronin-Coltsman.
Flesk Castle was built as a summer residence for the wealthy John Coltsmann. It has long fallen into ruin. It is now owned by the O’Reilly family, of American Irish background, who are consolidating the ruin. I look at that ruin, which is protected, and I look at the pre-famine stone cottage ruins at Coolcurtoga, which are not.
I regard them as equally important to our local heritage and history.
After all, Cronin-Coltsmann was once the owner of those too.
 Valerie Bary, Houses of Kerry, p114-115. The castle was otherwise known as Glenflesk Castle, Coltmann’s/Coltsman’s Castle, Killarney Castle, Dromhumper Castle, Droumhumper Castle.  The following illustrates early Coltsmann associations with the Killarney district: ‘On Thursday last Charles Herbert of Muckross Esq and the Rev Bastable Herbert, accompanied by 16 Gentlemen of the Killarney Volunteer Corps, under the command of John Coltsman Esq with eight of the 6th Dragoon Guards, proceeded from Killarney at 10 o’clock at night to the mountains of Glanflesk bounding the disturbed parishes of Ballyvourney and Iveleary, and after a difficult and harassing march through mountain passes and bye-ways, returned, bringing with them nine persons charged with Whiteboyism’ (Public Ledger, 18 February 1822).  ‘This noble edifice, the demesne, and the entire of the landed property pass into the possession of Mr Coltsmann’s nephew, Daniel Cronin jun Esq, eldest son of the hospitable proprietor of The Park. Mr Coltsmann served the office of High Sheriff for this county. His death throws the family of Sir William Godfrey, to whose most amiable lady he was brother, into mourning’ (Tralee Chronicle, 27 January 1849). John Coltsmann Esq died after a prolonged illness at his residence in Fitzwilliam Square, Dublin, Mary, daughter of John Coltsmann Esq of Flesk Castle, Killarney, married William Duncan Godfrey Esq of Kilcoleman Castle, Milltown, Co Kerry in Paris on 14 October 1824.  ‘Mr Coltsmann’s remains were on Monday last deposited in Muckross Abbey, beside his lamented sister, the late Mrs Cronin’ (Tralee Chronicle, 27 January 1849). Christina Coltsmann, daughter of John Coltsman Esq of Hinde Street, Manchester Square and wife of D Cronin jun Esq, died at Bellevue, Killarney, in June 1822 in the 25th year of her age. The square-shaped tombstone of the Coltsmann family in Muckross Abbey is inscribed on two sides. The side facing the Abbey is as follows: Pray for the Soul of/John Coltsmann Esq of Flesk Castle/Killarney who Died May 19th 1835/Aged 74 Years/Also for the Soul of his Wife/Christina Coltsmann who Died/January 24th 1838 Aged 63 Years/And of his Only Son John Coltsmann Esq who Died/January 16th 1849 Aged 54 Years/Requiescant [sic] in Pace. A notice of the death of John Coltsman senior Esq, which occurred at ‘Droumhoumper Castle,’ stated he was ‘at the advanced age of 87 years.’ (ref Kerry Evening Post, 20 May 1835). The death of his widow, Christina, in 1838, occurred at her residence, Grove End House, St John’s Wood, London. Her maiden name was de Lassence, said to have had a Portuguese background (Valerie Bary, Houses of Kerry).  John Coltsmann Esq married on 31 July 1839, at Southampton, to Catherine, second daughter of the late James Langdale Esq of Lavender-hill, Surrey. A panel of the square-shaped tombstone of the Coltsmann family in Muckross Abbey is inscribed: Pray for the soul of/Catherine Coltsmann/Widow of John Coltsmann/of Flesk Castle Killarney/Who Died November 13 1890/Aged 72 Years/Requiescat in Pace  Notes on the Cronin-Coltsmann family of Glenflesk Castle are given in Owen Roe O’Sullivan Son of Sliabh Luachra Biographical Sketch of Kerry’s Famous Bard with notes on Cronin of Rathmore House, The Park and Glenflesk Castle (2017) pp14-20. See also ‘Dicksgrove: Notes on the Families of Meredith and Coltsmann’ http://www.odonohoearchive.com/dicksgrove-notes-on-the-families-of-meredith-and-coltsmann/  The full story is given in ‘Coolcurtoga: A Story of Ireland’ http://www.odonohoearchive.com/coolcurtoga-a-story-of-ireland/