The Society runs mainline trains on the Irish railway network using steam traction and vintage carriages. Its longest running and most famous train, the Portrush Flyer, takes day trippers from Belfast to Portrush during the summer. Out of Dublin, several "Sea Breeze" trains are operated over the scenic Rosslare line to Wexford and Rosslare over the course of the Summer.
Each year the Society organises a major weekend event, operating usually from Dublin in May and covering major routes in Ireland at a leisurely pace. Many visitors return year after year from homes as far flung as New Jersey and Berlin. The 2008 tour operated to Waterford.
Excursion trains run throughout the year, primarily at weekends, from both Dublin and Belfast. A operational set of vintage carriages is kept both at Whitehead and in Dublin for these purposes. These trains are frequently packed to capacity, and advance booking is recommended.
The Society's founder members still perform regular maintenance tasks and undertake full engine restorations. They are joined regularly by new volunteers who assist in tasks from boiler repair to carriage painting. Volunteers are always welcome to visit and help at either of the engineering depots.
Its chief engineer and Locomotive Officer Peter Scott received an MBE for his services to the Railway Preservation Society in Northern Ireland in the Queen's Birthday Honours list, June 2006.
As of 2008, the society as three distinct rakes of carriages. One is made up of a mixture of NIR and BR mk2 vehicles, based at Whitehead. In Dublin, there exists two further rakes of carriages. One, the "heritage set", is mainly made up of 1950s vintage CIÉ Park Royal and laminate stock, along with some ex-GNR(I), GSR and GSWR vehicles. The other is made up of ex- Irish Rail Cravens coaches, along with a BR steam heating van.