Hello from Co. Offaly - and thank you for posting your message.
As you probably know, there are very few, if any, records for the early 1800's but having said that the name Troy is unusual so it may be possible to find something.
For example, in the Griffiths Valuation Land Survey (1847-64), there are a total of 47 Troy's listed in King's County. There is only one in the Barony of Philipstown - perhaps a sibling/parent of Ellen Troy?
http://www.askaboutireland.ie/griffith-valuation/index.xml?action=doNameSearch&familyname=troy&firstname=&offset=20&countyname=KING'S&parishname=&parishname&unionname=&baronyname=&totalrows=47&PlaceID=0&wildcard=
Griffiths Valuation Record Information
TenantFamily Name 1TROYForename 1MARYLandlordFamily Name 2MCDERMOTTForename 2MARCELLALocationCountyKING'SBaronyPHILIPSTOWN, LOWERUnionTULLAMOREParishKILLADERRYTownlandTOWNPARKSPlace NameMAIN STREETPlace TypeOTHERPublication DetailsPosition on Page56Printing Date1854Act15&16Sheet Number18,10Map Reference84 60
The Church of Ireland was the official church of the country at the time, so if there are any records they wil most likely be in the C of I registers. A good place to start searching for such records is the following addresses: http://ireland.anglican.org/information/64.
I also suggest that you contact the Offaly genealogy centre first to see if there are any records. The Irish Midlands Ancestry service can be contacted here:
http://www.irishmidlandsancestry.com/content/contact/contact_details.htm
info@offalyhistory.com/ Telephone + 353 (0)57 9321421.
Please note theirs is a chargeable service - there is a form on the website to complete and a first search costs ?10.
There are 21 Troy's in the Co. Offaly telephone book today - most around Ferbane and Kilcormac but 1 or 2 around Daingean which is the modern day area of Philipstown - if you could find some more information, the Ireland XO volunteers could help to perhaps find the ancestral lands or townlands.
Kind regards
Dolores O'Shea
Ireland XO Co-Ordinator for Co. Offaly
