Pat,
Thanks for the info about the descendants of Nicholas and Mary.
Below is some more information about the family. However my connection is not quite so straightforward as your guess, I'll explain later in the post.
In Kilsharvan cemetery (just off the road between Duleek and Julianstown) there are 4 Flinn graves, two of which are of particular interest in relation to this post. These two are a pair of identical headstones erected in 1851 set side by side in the wall of the ruined chapel. These stones are located in a small side room off the main chapel accessed through a small arch in the wall in which is fitted a wrought iron gate. This small room is maybe 8 foot square, and there are no other grave markers here apart from the two Flinn stones. Stamped on the gate are the letters R Flinn.
The inscriptions on the stones read as follows:
Left hand stone -
Erected by Richard, James and Christopher Flinn, Kilsharvan in memory of their Father Nicholas who died 3rd Novr 1844 aged 72 years. Also their brother John who died 14th April 1852 and their sister Catherine who died 25th February 1857. Also their Mother Mary who died 6th May 1860. Also his sister Anne Flynn who died 30th Decemr aged 35 years. Also the above Richard Flinn who died in February 18th 1903 aged 84 years. His sister Mary who died 22 March 1922 aged 105 years. And Mary daughter of the above James who died 2nd Jan. 1928.
Requiescant in Pace.
J. Maginn Drogheda. 1851.
Right hand stone -
Erected by Mrs. Bridget Flinn of Drogheda in memory of her belovd husband Richard Flinn who died 14th Augst 1849 aged 64 years. Also her daughter Mary who died 18th June 1847 aged 11 years. And of her son Richard who died young. Here also lieth the remains of the above mentioned Mrs. Bridget Flinn who departed this life the 31st December 1869 aged 73 years.
From the information I have found I believe that your great grandfather Nicholas Flinn was the son of the John mentioned on the left hand stone who died in 1852. This John married Ann Casey, they had at least 2 children - Nicholas (1847) and Mary Anne (1850).
I have followed up most of the rest of the names on the left hand stone:
Nicholas (d 1844) is listed in the Tithe Aplottment Books for Kilsharvan, I also know he worked as a carpenter.
Mary (d 1860) is listed in Griffiths Valuation
Catherine (d 1857) no further information, research ongoing
Anne (d ?) no further information
Richard (d 1903) never married, stayed in the house in Kilsharvan, worked as a carpenter
Mary (d 1922) never married, stayed in the house in Kilsharvan
James - died between 1870 and 1901, he married Mary Daly and they had at least 4 children: Mary (1862), James (1864), Anne Jane (1866) and Nicholas (1870).
Christopher - died 1904, he married Agnes Goodall in 1868 and they had 5 children: Richard (1867), Christopher (1868), Georgina (1870), Michael (1872), James Alexander (1879)
Richard and Bridget Flinn on the right hand stone turn up in connection with Skerries Mills and also a millwright business in Drogheda. At some point after Richard died in 1849 another Richard Flinn took over the millwright business, this Richard is my great great grandfather. This millwright business was not strictly confined to millwright work, but also produced a range of metal products and farming equipment, including gates.
Currently I am not sure how these families are related to each other, but I am pretty certain that they are. One of my current areas of research is tracing the descendants of all these families with the (small) hope that some information/clues may have been passed down one of the lines.
I have quite a few documents and other sources relating to these families, as well as photographs of the graves at Kilsharvan which I am happy to share, so I have sent you a private message containing my email address. Drop me a line and I'll send them on to you.
By the way my branch of the family remained in Drogheda for many years, though several left for the USA and England over the years, including my father who left for England in the 1930's. There are still quite a few cousins in the Drogheda area as well as many spread around the world. I grew up near Manchester, England and now live just outside Huddersfield.
Michael.