Archibald William Montgomerie, 13th Earl of Eglinton, 1st Earl of Winton, KT, PC (29 September 1812 – 4 October 1861), styled Lord Montgomerie from 1814 to 1819, was a British Conservative politician. He was Lord Lieutenant of Ireland in 1852 and again from 1858 to 1859.

Eglinton was born in Palermo, Sicily, the son of Major-General Archibald Montgomerie, Lord Montgomerie (30 July 1773 – 4 January 1814), the eldest son of Hugh Montgomerie, 12th Earl of Eglinton. His mother was Lady Mary Montgomerie (died 1848), daughter of General Archibald Montgomerie, 11th Earl of Eglinton. After his father's death, his mother married Sir Charles Lamb, 2nd Baronet.

He was educated at Eton.^[1] As a pastime he enjoyed playing golf. One of his playing partners was James Ogilvie Fairlie.^[2]

Eglinton was a staunch Tory. In 1846, he was a whip in the House of Lords; on 28 May 1846, he spoke against the Corn Importation Bill; in May 1848 he opposed the Jewish Disabilities Bill. ^[1]

In February 1852, he became Lord Lieutenant of Ireland under the Earl of Derby. He retired with the ministry in the following December. When Derby returned to office in February 1858 he was again appointed Lord-Lieutenant, and he discharged the duties of this post until June 1859.^[1][3]

In this year he was created Earl of Wintoun, an earldom which had been held by his kinsfolk, the Setons, from 1600 until 1716, when George Seton, 5th Earl of Wintoun, was deprived of his honours for high treason.^[3] Anstruther gives the date for this creation as 1840.^[4] The Earl's kinswoman, Georgina Talbot, in celebration of the restoration of the title, gave the slightly altered name 'Winton' then in Hampshire now Winton, Dorset to a residential development in Bournemouth, which she was creating at this time.^[5]

Lord Eglinton married, firstly, on 17 February 1841, Theresa Howe Cockerell, née Newcomen, widow of Captain Richard Howe Cockerell RN (1798–1839, buried Park St, Calcutta). Mrs Cockerell was an illegitimate daughter (out of 8 children)^[7] of Thomas Gleadowe-Newcomen, 2nd Viscount Newcomen (1776–1825) and his long-term mistress Harriet Holland. Theresa Newcomen was born in Calcutta in 1809, and died on 16 December 1853 at Eglinton Castle. They had the following children:

• Archibald Montgomerie, 14th Earl of Eglinton (1841–1892)
• Lady Egidia Montgomerie (c. 1843–1880), who married Frederick Thellusson, 5th Baron Rendlesham.
• Hon. Seton Montolieu Montgomerie (1846–1883), who married and left daughters.
• George Montgomerie, 15th Earl of Eglinton (1848–1919), ancestor of the present Earl.

According to Eglinton's entry in the Oxford Dictionary of National Biography, as cited here, this marriage was the great mistake of his life. However, his stepdaughter Anna Theresa Cockerell (1836–1912), aided by her mother's second marriage, went on to marry Charles Chetwynd-Talbot, 19th Earl of Shrewsbury.

After Theresa's death in December 1853, her widower married, secondly, the Hon. Adela Caroline Harriett, daughter of Arthur Capell, 6th Earl of Essex, in 1858. They had the following children:

• Lady Sybil Amelia Montgomerie (d. 1932)
• Lady Hilda Rose Montgomerie (d. 1928), who married Tonman Mosley, 1st Baron Anslow and died at Bangors, Iver, Buckinghamshire.

Lady Adela died in December 1860, aged only 32. Lord Eglinton survived her by less than a year before dying at Mount Melville House, near St. Andrews, on 4 October 1861, and was buried in the family vault at Kilwinning, Ayrshire, on 11 October 1861. He was succeeded by his eldest son Archibald.^[1]

• Eglinton Country Park
• Eglinton Tournament Bridge