A huge huge thankyou to Moscan who has found information from a number of different sources for me on this subject. She consulted the Wicklow library service on my behalf and I now have various documents on the House, the area and local villages, the O'Reilly family and some Cuthbert references to follow up.
Special thanks also to Christopher for all the suggestions and to Robert of the Wicklow library service for all his efforts and the documents he found for me.
By chance today I found another piece of the jigsaw through a link from Rootschat to the Tracy family website.
From: 1771 to 1812 Walkers Hibernian Magazine
O'Reilly, Capt. John Tracy (late of 5th Dragoons), of H.E.I. Co.'s 3rd Regt. of Native Cavalry=Hunter, Isabella Sarah, only child of Andrew, of Queen St., Edinburgh, late of Bengal, in St. Mary's Church, at Madras, 1 July, 1807 Jan. 1808 p. 62
...
which confirms that the John T O'Reilly of Kilquade House mentioned in our apprenticeship document married Isabella Sarah Hunter, .... linking to the name of Hunter O'Reilly - presumably their son and heir, and giving me more details on the person named as Robert Cuthbert's employer.
.. another brickwall is crashing down...
I'm off to have a really good look through all these papers. it feels like Christmas!