Irony of Fate
(The). A strange fatality which has brought about something quite the reverse of what might have been expected.
“By the irony of fate the Ten Hours' Bill was carried in the very session when Lord Ashley, having changed his views on the Corn Laws, felt it his duty to resign his seat in Parliament.” —The Leisure Hour, 1887.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894