Gailey was born in County Donegal, Ireland and emigrated to Australia in 1864, becoming an influential and prolific architect in colonial-era Brisbane.

He died in Brisbane on 24 April 1924, two days after his ninetieth birthday, and is buried in Cleveland Cemetery along with his wife Mary, née Rice.

[1][2] His substantial body of work includes many commercial and residential buildings in Brisbane that today are considered colonial treasures.

Some of these include: In addition to his architectural work, Gailey was also a licensed surveyor and responsible for surveying and laying out the town of Bowen.

[10][11] Gailey's work combines the practical value in a sub-tropical environment of high-thermal mass masonry walls with the aesthetic value of finely detailed arches creating a wide veranda to shade the load-bearing walls from the sun during the hottest part of the day.