A military diploma found in Morocco attests that he was suffect consul on 18 August for one of the years between 129 and 132 as the colleague of ...cus Priscus.
Hans-Georg Pflaum speculates his grandfather may have been one of the signatories to a promulgation of Lucius Helvius Agrippa, proconsul of Sardinia, dated 18 March 69.
[4] The earliest office Gallus is recorded as holding was quaestor, which he discharged in the province of Asia; upon completion of this traditional Republican magistracy he was enrolled in the Senate.
[5] Following this, Gallus was appointed legatus legionis or commander of the Legio III Gallica stationed at Raphaneae in Syria.
At this point, historian Mireille Corbier comments, "The prefecture of the aerarium Saturni is the culmination of a long line of Praetorian posts that led our senator to the four corners of the empire, and the consulate is the normal conclusion of a well-conducted, but uninspired (mais sans éclat) career".