Alexander Forbes Irvine
Portrait of Alexander Forbes Irvine, painted by Sir George Reid.
Born	18 February 1818 Schivas House, Tarves, Aberdeenshire, Scotland
Died	4 April 1892 Drum Castle, Scotland
Nationality	Scottish
Education	Marischal College, University of Aberdeen; University of Edinburgh
Occupation(s)	Landowner, Advocate, Philosopher, Amateur Astronomer
Known for	Prominent member of Clan Irvine, Dean of the Faculty of Advocates, Principal Clerk of the Justiciary Court, Sheriff of Argyll, Fellow of the Royal Society of Edinburgh
Spouse	Anna Margaretta Forbes-Leslie (m. 1848)
Children	Alexander Charles Quentin Hamilton Irvine, Francis Hugh Forbes Irvine, 21st Laird of Drum
Parent(s)	Margaret Hamilton and Alexander Forbes Irvine, 19th Laird of Drum

Alexander Forbes Irvine, 20th Laird of Drum FRSE JP DL LLD (1818–1892) was a Scottish landowner, advocate, philosopher and amateur astronomer. He was a prominent member of Clan Irvine and held the family seat of Drum Castle until his death.^[1]

He was born at Schivas House near the village of Tarves in Aberdeenshire on 18 February 1818, the son of Margaret Hamilton^[2] of the Hamiltons of Little Earnick, and Alexander Forbes Irvine, 19th Laird of Drum (1777-1861). He was a friend of his near neighbour, Cosmo Innes, and their careers followed very parallel paths. Other friends included William Forbes Skene of Rubbislaw and Sir David Lindsay.^[3]

He was home tutored rather than attending school, then studied law first at Marischal College in the University of Aberdeen then at the University of Edinburgh.^[4] He passed the Scottish bar as an advocate in 1848 and rose to be Dean of the Faculty of Advocates. He was Principal Clerk of the Justiciary Court 1867 to 1874 and Sheriff of Argyll from 1874 to 1891.

He inherited the Drum Estate in 1861, on the death of his father. In 1875/1876, he arranged for a restoration of the courtyard, and the addition of an arched entrance and angle tower.^[5][6] He was also partly responsible for a restoration of the chapel.^[7]

In 1878, Forbes was elected a Fellow of the Royal Society of Edinburgh. His proposers were Sir Alexander Grant, Charles Neaves, Lord Neaves, Edward Sang and Peter Guthrie Tait. He twice served as Vice President to the Society: 1883 to 1887 and 1890 to 1892.^[8]

In 1886, he co-founded the New Spalding Club.^[9] In 1887 the University of Edinburgh awarded him an honorary doctorate (LLD).

He died at Drum Castle on 4 April 1892.

In 1848 he married Anna Margaretta Forbes-Leslie (d.1900), daughter of Lt Col Jonathan Leslie of Rothienorman, a noted amateur archaeologist.

Their children were Alexander Charles Quentin Hamilton Irvine and Francis Hugh Forbes Irvine, 21st Laird of Drum (1854-1894).

He was survived by two brothers: James Hamilton Irvine, who went to live in North Gippsland in Australia; and Sir Charles Irvine of the Indian Army.

He was painted by George Reid PRSA.

• Genealogy and other facts, citing Burke's Peerage