There certainly appears to be elements of irony in the speaker's entire journey in Philip Larken's "The Whitsun Weddings." As the speaker's journey begins, the train is nearly empty. It is a hot day, and the speaker does not find any particular relief as the train travels through the countryside. The cushions in his compartment stink. He sees "industrial froth" in the canals. Sometimes the smell of grass becomes overwhelming. He notices "acres of dismantled cars" that are now worthless clutter. There is certainly irony here, for the excitement of a train ride in the country is not at all what it is cracked up to be.
At first, the speaker does not notice the wedding parties gathered at the stations where his train stops. Apparently, this Sunday is a prime time for weddings, for a newly married couple boards the train at nearly every station, and pretty soon the speaker begins paying attention. He is not, however, struck by the romance or the beauty of these wedding parties. Rather, he focuses on the overdressed young ladies who parade around "in parodies of fashion," thinking that they look splendid when they only look rather silly. Notice the irony at their expense.
The speaker sees older people as well and thinks about how they look worn-out and fat even though they try to be fancy. The young people will eventually get that way, too, he thinks. The fathers, though, stand as though they have just experienced their greatest success in marrying off their children. The women share their secrets "like a happy funeral," and the girls seem to stare at a "religious wounding." Notice here the strong irony about marriage, which is what these two phrases describe.
The couples themselves pack onto the train for London with no idea of what their lives will be. The speaker thinks about how these young people have limited themselves by their marriages. There are people they will never meet and experiences they will never have. Again, here is irony, for the speaker presents a whole different side of marriage on this journey.