Birthplace:
- County Limerick, Ireland

Birthdate:
- 10 February 1844

Nationality:
- Irish

Height:
- 5 feet 9 inches

Family Background:
- O'Grady's father was Standish Thomas O'Grady, owner of Landscape, County Clare, Ireland. His mother, Thomasina, was the daughter of Gerald de Courcy O'Grady ('the O'Grady') of Killballyowen, County Limerick, Ireland.

At Sandhurst:
- Yes

Foreign Languages:
- French and German

Career before Halifax:
- Ensign, 2 October 1866 (non-purchase)
- Lieutenant, 25 April 1865 (purchase)

Postings while in NS Command:
- Halifax, 9 May 1869 to 2 June 1870
- to Scotland, 3 June 1870

Career after Halifax:
- retired by sale of commission, 8 June 1872

O'Grady's parents were both of distinguished Irish (and O'Grady) lineage. After attending the English public school Rugby, O'Grady entered Sandhurst. Like Lieutenant Charles Roberts he was one of those who passed out high enough to qualify for one of the number of non-purchase commissions which were available each year to a select number of Sandhurst graduates.

A letter written to the Horse Guards on his behalf by a family friend at the time that he was looking for a regiment stated that "although an Hibernian he is very anxious to wear the kilt - in that his first desire is to be appointed to the 42nd Regiment". A commission in the latter not at the time being available, O'Grady accepted one in the 78th, "also a kilted regiment."

O'Grady sold out of the army less than a year after the 78th left Halifax. In 1876 he succeeded to the ownership of the Landscape estate, and he is listed in Edward Woolford's County Families of the United Kingdom (1878) as "Gilbert O'Grady Esq. of Castle Mahon, co. Limerick, and of Landscape, co. Clare."