In 1855 five Sisters of Mercy left St. Leo’s, Carlow to go to Alton, Staffordshire, England at the invitation of the Earl of Shrewsbury, who had given a house on his estate for a convent so that children living nearby whose parents were engaged in the Potteries would have a religious education. The Potteries is now the unique city of Stoke on Trent, originally six separate towns in North Staffordshire, the home of the pottery industry in England since the seventeenth century with world renowned names such as Royal Doulton, Spode, Aynsley and Minton. The Earl died without heirs and his property ‘Alton Towers’ passed to the next of kin who were protestant. The grant towards the maintenance of the convent and school was withdrawn.
In 1873 four Sisters left Alton for Borris in Ossory, Co Laois. It was intended that the rest would follow but it was found that four were sufficient. Mr Patrick Kehoe whose three daughters Srs. M. Xavier, Ignatius and Evangelist were part of the Alton community was a relative of Fr. John Nolan, Parish Priest of Rathangan, Co Kildare. When he was left a large sum of money he expressed to Fr. Nolan that he would like it to be used to secure a place for the remainder of the Alton Sisters. In Rathangan there was a small house with ten acres of land rented from a Quaker family named Pim in which the curates of the parish lived. Fr. Nolan began negotiations and in July 1874 wrote to Sr. M. Ignatius Kehoe in Alton explaining that he wished to establish a convent in the parish and telling her what was set in place for the sisters should they wish to come – a house, school, land and money.
On 1st June 1875 Srs. M. Magdalen Monaghan, Ignatius Kehoe, Xavier Kehoe and Aloysius Nagle came to Rathangan. They were formally presented to the parish by Dr. James Lynch, co-adjutor bishop of Kildare and Leighlin on 15th August, the occasion of confirmation in St. Patrick’s Church. Many gifts were presented to the Sisters, a harmonium, statues, pictures, books and a ciborium and a sanctuary lamp. A local man, Mr. Stephen Murphy, got a wall built to enclose the convent and a field. Several Postulants entered, Anne Byrne (Sr. M Evangelist) 21st June 1875, Mary Lacy (Sr. M. Stanislaus) 15th August 1875, Anne Flanagan (Sr. M. Gertrude) 1st January 1878, Anne Hyland (Sr. M. Teresa) 19th October 1880, and Elizabeth Ball (Sr. M. Patrick) 16th March 1882. Sr. M. Ignatius Kehoe died 22nd March 1882 aged forty two.
The Sisters taught in a school which had been run by two ladies named Dalton. They provided primary education for girls and taught cookery and needlework. A new convent was built in 1879, the old one renovated into classrooms and, as well, outhouses were transformed and continued as a girls’ primary school until 1955. Then a new primary school was built on the convent grounds. The Sisters taught in the Primary school until 2003. Sr. Rosarii Murphy was the last Mercy Principal and Sr. Ailish O’Brien the last Sister who taught in Bunscoil Bhríde. The old primary school continued to be used for Post Primary education until 1986. In 1971 it had been merged with the local vocational school to become Rathangan Post Primary school. Ardscoil Rath Iomhgain a new Post Primary building opened in 1986. The last Mercy Post – Primary Principal, Sr. Brigid Morgan retired in 1989 and Sr. Bernadette Sheerin continued to teach in Ardscoil Rath Iomgháin until 2006.