[2] As the first person appointed to Chief Engineer J. J. C. Bradfield's team, as his Confidential Secretary, (a role which today would be called a technical adviser or project planner), she managed the international tendering process and oversaw the development of the technical plans, travelling to London in 1924 to supervise the project in the offices of Dornan's, the company which won the tender.

[5][3] She joined the staff of the Chief Engineer of metropolitan railway construction, when the branch was established in 1912 to deal with Sydney's transit problems.

[1] She was "appointed on her merits" and was involved in all aspects of the project planning and acted as the lynchpin for information flow, as she had mastered all sorts of intricate technical matters of engineering.

[7] Butler wrote numerous articles about the development of Sydney Harbour Bridge between 1922 and 1927, in effect acting as the PR for Bradfield's office.

[10] In March 1922, Bradfield left Australia and travelled abroad, undertaking research into possible bridge tender proposals on the instructions of the government.

"[17] Once the British firm Dorman Long were appointed on 26 February 1924, Butler lost no time in publicising the specifics of their plans, writing an indepth newspaper article about Our Harbour Arch Bridge: The World's Record in the Sydney Mail on 12 March 1924.

"[17] Dorothy Donaldson Buchanan, the first woman in Britain to gain qualification as a civil engineer, was working on the bridge project in the same Dorman Long offices at this time.

Her arrival in London featured in both the suffrage magazine The Vote and in several gossip columns which complimented her expertise and noted her interest in surfing, tennis and dancing.

[24] In January 1925 her family threw her a party in Lithgow where she announced that she would "return to Sydney on Monday and on Tuesday enter in earnest on the six-years job of constructing the harbour bridge".

[26] She was present at the ceremony of the turning of the first sod for the North Railway Approach to the bridge and she was publicly thanked for her services.

[29] She undertook site visits with the project engineers, including the inspection of the excavation for the south west skewback.

[31] Her leaving gift was a grandfather's clock, given as a token of "the good will and esteem of the officers of the Sydney Harbour Bridge and Metropolitan Railway Construction Branches and of the Public Works Department" and Bradfield's statement that "Miss Butler's capability led to her attaining the position of trust and responsibility she held in the Department, and that her retirement would be a distinct loss to the Bridge branch".

On 20 April 1927, Butler married Maurice Hagarty, a grazier from Cunnamulla, Queensland, in St Mary's Cathedral, Sydney.

When her grandchildren came to stay she had the garden piled with sand to replicate what they knew from their home in the outback to make them feel more comfortable.

[38][39][40][41][42] In 2022, Butler was chosen as one of the notable people buried in Macquarie Park Cemetery whose life stories were told on video as part of the commemoration of the burial ground's centenary.

[37] In November 2023, it was announced that Butler was one of eight women chosen to be commemorated in the second round of blue plaques sponsored by the Government of New South Wales alongside, among others, Emma Jane Callaghan, an Aboriginal midwife and activist; Susan Katherina Schardt; Dorothy Drain, one of Australia's first female war correspondents; writer Charmian Clift; Pearl Mary Gibbs, an Aboriginal rights movement activist; and charity worker Grace Emily Munro.

[43][44] The plaque was unveiled on 6 August 2024 at Butler's former place of work, the Chief Secretary’s Building in Phillip Street, Sydney.