The first President of the New Zealand Law Society, Reid was also the first non-political holder of the role of Solicitor-General which he held for 25 years – the longest tenure ever. He was highly respected as an expert law draftsman and constitutional lawyer.

Reid was born in Edinburgh in 1839. His father was an Army officer and was sent to Tasmania in 1852 with his family. After completing his schooling Walter worked for the Launceston law firm of Douglas & Dawes and qualified as a barrister and solicitor on 14 October 1862. While in Tasmania he married Mary Jane Hume. The couple had two sons and a daughter.

Reid moved to New Zealand from Tasmania in 1865. He initially practised as a lawyer in Wellington (in partnership with JA Buckley, later Justice Buckley). In early 1866 he moved to Invercargill on his appointment as Registrar of the Supreme Court, Southland. He then moved to Hokitika where he practised in partnership with CE Button (later Justice Button). While in Hokitika he was appointed Chair of the Board of Education for the County of Westland. In 1871 he was elected to the Westland County Council.

Reid began a career in the Crown Law Office as assistant law officer in 1872. When James Prendergast, who had been Attorney-General, was appointed Chief Justice, the Attorney-Generalship was left vacant for 18 months and the permanent non-political office of Solicitor-General was established. In 1875 Reid became the first non-political holder of that office and New Zealand's second Solicitor-General. The salary was £1,000 a year. He was to hold the office for a quarter of a century.

During his term of office the work of the Crown Law Office was mainly advisory and drafting and was carried out by Reid and two assistant law officers. So far as is known Reid never appeared as counsel for the Crown. During the first 18 months and the last five years of his term as Solicitor-General the office of Attorney-General was vacant and Reid was Senior Law Officer of the Crown.

His duties were not confined to those as solicitor for the Crown. One of his first tasks as Solicitor-General was to draft the Abolition of Provinces Act 1875 and he came to be recognised as an authority on constitutional law. As a commissioner with Justice Johnson, under the Revision of Statutes Act 1879 he was jointly responsible for the 1880 consolidation of existing New Zealand statutes and the adaptation of the Criminal Code, eventually enacted in 1893.

In 1882 Reid was a member of the Judicature Commission which prepared the code of civil procedure. He also chaired the Boards of the Public Trust Office and the Government Insurance Department.

After his first wife Mary died, Reid married New Plymouth-born Emma Halse (1852-1920) in 1895.

Reid was active in the affairs of the Wellington District Law Society and was President in 1893. On 3 May 1897 he was unanimously elected first President of the New Zealand Law Society, following passage of the Law Practitioners and New Zealand Law Society Acts Amendment Act 1896 which aimed to revitalise the New Zealand Law Society.

His term as President was marked by some uncertainty as to the powers and strength of the Law Society. There was also an acute shortage of money. Portrait of a Profession notes there were doubts "as to whether the Society's constitution was sound and whether those elected to office had been validly appointed. One of the difficulties apparently felt was that the first meeting may not have been properly convened, there having been no President at the time." (page 151).

It was not until 1902 – after Reid had ceased to be President – that a validating Act was passed. It is perhaps significant that Reid's relatively long obituary in the Evening Post makes no mention that he had been the first President of the New Zealand Law Society.

He retired as Solicitor-General in November 1900, having been granted a pension of £500 a year. He also resigned from the Council of the Wellington District Law Society and was replaced as President of the New Zealand Law Society by Henry Dillon Bell early in 1901.  

A farewell ceremony and presentation from the legal profession was held in the Supreme Court in Wellington on 10 January 1901. The Evening Post reported that he was presented with an illuminated address which "expressed appreciation of Mr Reid's many eminent services to the colony and the legal profession; noted his firm grasp of legal principles, as well as his profound knowledge of constitutional law. As the colony's chief law officer he had combined in an eminent degree the qualities required in the high and onerous position he had occupied with such credit to himself and advantage to the colony. He had taken a keen interest in all matters relating to the welfare of the legal profession, and acted on the Councils of the New Zealand and Wellington District Law Societies, from whose deliberations he will be much missed."

Reid appears to have been content to remain in the role of Solicitor-General. The Cyclopedia of New Zealand said he was considered "by the highest legal authorities to be the best constitutional lawyer in the Colony since the death of Sir Frederick Whitaker. He has more than once been offered and refused a Supreme Court judgeship, but his health, apart from other considerations, has led him to decline the honour." Henry Dillon Bell noted in 1901 that he had been an "ambassador from the Government" to persuade Reid to accept a seat on the Supreme Court Bench.

During the early years of his retirement Reid was involved with the Chief Justice and the Solicitor-General in working on the Consolidation of Statutes, which finally occurred in 1908. In 1905 he was appointed chairman of the Land Commission.

Reid died in Wellington on 31 January 1920 aged 81. It was reported that he had been in ill health for a considerable time before his death and he had been confined to bed for many months.

Sources: Evening Post, 1 November 1862, page 4; Evening Post, 19 December 1865, page 6; "Crown Law Office", Cyclopedia of New Zealand, Wellington Provincial District, (The Cyclopedia Company Ltd, 1897), pages 135 and 136; Evening Post, 12 September 1900 page 5; Press, 26 September 1900, page 5; Evening Post, 11 January 1901, page 7; Evening Post, 2 February 1920, page 7; Evening Post, 3 February 1920, page 8; Evening Post, 12 April 1920, page 8; "WS Reid" by ILM Richardson, Portrait of a Profession (AH & AW Reed, 1969).