Rumour has it that the Railway Preservation Society of Ireland was set up to encourage drinking on Good Friday. The society swears it's not true, but to the passengers on the 2.15 p.m. to Mullingar, it seemed as good a reason as any.
"I don't know what it is but the pints taste better when you're moving. I've a bar in my own house, but I'd rather be here," Morris Coen, a Dublin Bus worker, said.
For many it was the observance of the Good Friday tradition, of getting a drink at all costs, that brought them aboard the society's regular jaunt to Mullingar, but for others it was pure nostalgia.
"The last time I was on a steam train was in 1967, going down to Cork, or was it Limerick, for a Munster final, whenever it was it was a great day," said Mr Jim Kelly, from Tipperary, who although claiming to be a devout Catholic was enjoying a pint of plain.
"I've always loved the trains. I can remember when I was small watching the steam trains at Laffan's Bridge Station. They could have been going off around the world."
For William Cummins from Meath, enjoying his pint was a matter of principle. "Every shop in the country is open, all the supermarkets, and I don't see why the pubs shouldn't be allowed to. The pub is more part of our culture than Marks and Spencer," he said.
However, it was the atmosphere of the train more than the pint that was important, he said.
"I've been taking these trips for five years. They're totally relaxing. No one's going anywhere in a hurry. People love going back in time, and it's a very real aspect of what people did long ago."
The train itself has a timeless air, in that it would be impossible to place it in any one period. The black engine is from 1947; part of the Northern Counties Committee railway stock, it pulled the last scheduled steam train in Ireland in 1970.
The oldest carriage, built in Inchicore in 1921, looks like it was snatched from the set of a Merchant Ivory film, with separate compartments for six passengers. The restaurant car, described as being from De Valera's time, has loose wooden tables and chairs, rather than the bolted-to-the-floor type. Other carriages are from the 1940s, 1950s and right up to the ultra-modern-looking 1960s.
The stock has all been salvaged from the Great Southern, Great Western and Great Northern Railways along with the earlier years of CIE. However, a number of passengers remarked that the train seemed very similar to the Iarnród Éireann one they got to Sligo last week.
"The best thing about the train is that it goes really fast," said seven-year-old Stephen Lyons as it reached its top speed of 55 m.p.h. His sister, Eimear (5), said the best thing was she could see her house from it.
Seven-year-old Aaron Carroll Moran had come all the way from Mayo for the trip, because, he said, "I'm mad for trains".