[2] He was educated at Calder House, Redfern, and joined the government Works Department in 1878 as a cadet.

In 1900, he was appointed Principal Assistant Engineer for Rivers, Water Supply and Drainage, and supervised the completion of the Sydney low level sewerage system, which was a pumping system to replace harbour sewage outfalls.

He returned to the Public Works Department in 1912, and had overall design responsibility for the steel Pratt truss–type Tom Uglys Bridge over the Georges River.

He was awarded a Telford Premium by the Institution of Civil Engineers for a paper on port improvements in Newcastle, including excavation of the channel and extension of the breakwater.

[6] Allan retired from the public service in March 1926;[7] and died suddenly at his home in Darlinghurst on 7 May 1930.