Buchanan, Dorothy Donaldson [Dot] (1899–1985) civil engineer, was born at the Manse, Langholm, Dumfriesshire, on 8 October 1899, the youngest of five children of the Revd James Buchanan (1843/4–1921), minister of Langholm, and his wife, Marion, née Vassie (1863/4–1930). There was nothing in her family’s clerical and medical background to encourage an interest in civil engineering, though Langholm had traces of the early work of Thomas Telford, the local mason who became the leader of the civil engineering profession. This inspired her interest and, after attending Langholm Academy, she successfully applied in 1918 to study for a BSc degree in civil engineering at Edinburgh University, where in 1919 another woman (Elizabeth Georgeson) graduated in engineering, the first woman to do so in Scotland. Having suffered from mumps while a student, Buchanan took four years to complete the course, graduating in 1923.

Following graduation Buchanan contracted pneumonia, and was recommended a change of air to aid her recovery. Intending to train as a civil engineer, she went to London, armed with a reference from Thomas Hudson Beare, who had taught her. Initially rebuffed, she learned that Ralph Freeman, by then senior partner in Douglas Fox & Partners, was recruiting a team to work on the design of Sydney Harbour Bridge, for which he was acting as consultant to the steelwork contractors Dorman Long & Co. Impressed, he allowed her to join the bridge design staff at Dorman Long’s London office for £4 a week plus overtime. She was his pupil under agreement from April 1924. She was regarded as a curiosity, and male colleagues came to gawp at this female engineer. As well as Sydney, she worked on the design of overseas bridges at Dessouk and Khartoum (Omdurman).

In May 1926, to obtain site experience necessary for the Institution of Civil Engineers (ICE) qualification to supplement her work in the design office, Buchanan went to Northern Ireland to work on the Silent Valley Reservoir built for the Belfast water supply by S. Pearson (1923–33). Freeman’s role as mentor was taken on by Sir Ernest Moir. She had the attentions of a chaperone, whom she escaped by setting out for work before she arrived. After six months she returned to England to work again for Dorman Long’s bridge design team, and then worked on the design of the steelwork for King George V (Tyne) Bridge in Newcastle upon Tyne (built 1925–28), and Lambeth Bridge (built c.1928–1932).

In 1924 a woman (Helen Grimshaw) studying engineering at University College, London, applied for student membership of the ICE. The professional body sought legal advice, which confirmed that in the light of the Sex Disqualification (Removal) Act of 1919, ‘women are eligible for membership under the Charters as now in force and may, under the bye-laws, be admitted as students and subsequently as members’. The applicant did not take her membership further. In May 1927 Buchanan, who was working in an office where most of her colleagues were becoming qualified ICE members, applied to the ICE for admission as an associate member (AMInstCE), the then grade of professional qualification (CEng MICE in 2017). This involved having passed degree-level examinations and practical experience. At the time applicants had to pass an interview discussing their experience. As she believed she was the first woman to reach this stage in the membership process she was surprised to find another woman waiting at the ICE offices in Great George Street, Westminster, in October 1927. The other woman politely explained that the institution had felt it should provide a chaperone for the day. She was elected an ICE member on 13 December 1927 following a successful interview, the first woman in Britain to gain qualification as a civil engineer.

On 14 June 1930 Buchanan married, at St Columba’s, Pont Street, Kensington, William Hamilton Dalrymple Fleming (1901–1986), an electrical engineer; he was the son of Archibald Fleming DD, a Church of Scotland minister of St Columba’s, who officiated at the ceremony. They had no children.

Despite her recent success in obtaining her professional qualification, Buchanan cut short her career as an engineer following her marriage. However, she was conscious of her pioneering role and nearly fifty years later remarked: ‘I felt that I represented all the women in the world. It was my hope that I would be followed by many others’ (New Civil Engineer, 6 July 1978, 15–16). She pursued alternative interests in rock climbing and painting. She died at her home at St John’s Hospital, Axbridge, Somerset, on 13 June 1985.