While most British publications have adopted the newer spelling of jail, many Australian publications, along with a few British and Irish holdouts, still use the older spelling, gaol
Example
Even in Australia, where gaol is most common, jail is used much of the time—for example:
Williamson is allowed out of jail up to twice a month to visit banks, supermarkets and post offices. [Sydney Morning Herald]
The charge brings the star a step closer to jail. [The Age (Melbourne)]
Gaol also appears with some frequency in Irish publications—for example:
The Hobans were remanded in Galway gaol! [Galway Advertiser]
But in Ireland as well as in Australia and everywhere else, jail predominates.
Like many archaic words, gaol lives on in place names—for example:
A skull once displayed at Old Melbourne Gaol is thought to be Deeming’s or that of notorious outlaw Ned Kelly. [BBC News]
His love of history started at a young age as he walked from his house to spend an afternoon exploring the Kilmainham Gaol … [Roll Call]
But most publications would refer to such institutions as jails when not using their proper names.
Ngrams
This Ngram, which charts instances of the two words used in British books published from 1800 to 2000, shows the decline of gaol in British English over the last two centuries.
