Moncreiff was born on 29 November 1811 to Ann, daughter of George Robertson, R. N. and
Sir James Wellwood Moncreiff, 9th Baronet, a Scottish judge. He was born at his parents' Edinburgh townhouse on 13 Northumberland Street. He was educated at
Edinburgh High School then studied law at the
University of Edinburgh and was admitted to the
Faculty of Advocates in 1833. He was appointed
Solicitor General for Scotland in 1850, and
Lord Advocate from 1851 to 1852, from 1852 to 1858, from 1859 to 1866 and from 1868 to 1869. He was
Dean of the Faculty of Advocates from 1858 to 1869. He was appointed
Lord Justice Clerk from 1869 to 1888. In 1856, he defended the
Scotsman in the libel action raised by
Duncan McLaren, one of the members for the city of Edinburgh. In January 1857, Moncreiff was presented with the freedom of his native city for the part he took in regard to the
Municipal Extension Act. In 1859 he was appointed
Lieutenant-Colonel Commandant of the newly formed
1st Queen's Edinburgh Rifle Volunteer Brigade (No 1 Company of which was recruited from Edinburgh advocates) – the first rifle volunteer corps in Scotland. He held the appointment until 1873 when he was appointed
Honorary Colonel. In 1860, he helped pass the annuity tax bill, a subject in which, as a free churchman, he took close interest, and in the following year he carried the major bill relating to burgh and parochial schools. In 1861 he was engaged as leading counsel in the defence of
Sir William Johnston, one of the directors of the Edinburgh and Glasgow bank, and in 1863-4 he was counsel in the famous
Yelverton case. For 19 years Lord Moncreiff occupied the judicial bench, presiding over the trials in the justiciary court of
Chantrelle (1878), the
City of Glasgow Bank directors (1878), the
dynamitards (1883), and the crofters (1886). Extrajudicially Moncreiff was occupied in many other matters. As a lecturer he was in great request, and delivered numerous orations in Edinburgh and Glasgow on subjects of literary, scientific, and political interest to the Philosophical Institution, Royal Society, Juridical Society, Scots Law Society, and other bodies. Moncreiff also published anonymously in 1871 a novel entitled
A Visit to my Discontented Cousin, which was reprinted, with additions, from ''
Fraser's Magazine. He was also a frequent contributor to the Edinburgh Review''. In 1858 Moncreiff received the honorary degree of LL.D. from the
University of Edinburgh. From 1868 to 1871 he was rector of the
University of Glasgow from which he received a second honorary doctorate of LL.D. in 1879, and in 1869 he was appointed a member of the
Privy Council. On 23 May 1871 he was created a
baronet of Kilduff in the County of Kinross in the
Baronetage of the United Kingdom. On 9 January 1874 he was created
Baron Moncreiff, of
Tulliebole in the
County of Kinross in the
Peerage of the United Kingdom; in 1878 he was appointed a royal commissioner under the Endowed Institutions (Scotland) Act, and in 1883 he succeeded his brother as 11th baronet of
Moncreiff. In 1875, he became the inaugural President of the conservationist group the
Cockburn Association, a position he held until 1893. In September 1888, Moncreiff resigned the position of Lord Justice Clerk, and took up the preparation of his
Memorials. On these he was engaged till his death on 27 April 1895. He is buried with his wife in
Dean Cemetery in west Edinburgh. ==Artistic recognition==