John Macdowall1 
Colonel William Macdowall, 1st of Castlesemple1 
He gained the rank of Colonel in the Briitsh Army, served in St Christopher’s, West Indies, where he acquired a considerable plantation.1 In 1727 he purchased the ancient barony of Castlesemple in the parish of Lochwinnoch, Renfrewshire, from 11th Lord Sempill , also other baronies.1
Child of Colonel William Macdowall, 1st of Castlesemple and Mary Tovey
- William Macdowall, 18th of Garthland and 2nd of Castlesemple+2 b. 1700, d. 1776
Children of Colonel William Macdowall, 1st of Castlesemple and Isabella Wallace
- John Macdowall+2
- James Macdowall2 b. 1740
- Elizabeth Macdowall+2 b. Apr 1742, d. 12 Oct 1778
Mary Tovey1
Her married name became Macdowall.
Child of Mary Tovey and Colonel William Macdowall, 1st of Castlesemple
- William Macdowall, 18th of Garthland and 2nd of Castlesemple+2 b. 1700, d. 1776
William Macdowall, 18th of Garthland and 2nd of Castlesemple1 
He was recognised by Lord Lyon King of Arms, and matriculated his arms at the Lyons Court on 21 April 1749.3
Children of William Macdowall, 18th of Garthland and 2nd of Castlesemple and Elizabeth ‘Black Bess’ Graham
- William Macdowall, 19th of Garthland and 3rd of Castlesemple3 b. 17 Nov 1749, d. 2 May 1810
- Mary Macdowall+3 b. 26 Jan 1751, d. 2 Jul 1782
- James Macdowall+3 b. 20 Jan 1752, d. 30 May 1808
- Day Hort Macdowall+4 b. 27 Mar 1753, d. 16 Jun 1809
- Alexander Macdowall3 b. 8 Jan 1755
- Anny Macdowall+3 b. 2 Feb 1756
- Betty Macdowall3 b. 15 Jan 1757
- John Macdowall3 b. 11 May 1758
- Lt.-Gen. Hay Macdowall3 b. 12 Nov 1759, d. 1809
- David Macdowall+4 b. 20 Jul 1761, d. 1841
- Graeme Macdowall5 b. 25 May 1763, d. 19 Mar 1833
- Lt.-Col. Lawrence Macdowall3 b. 26 Aug 1764, d. 1815
- [S32] BLG2001 volume 1, page 883. See link for full details for this source. Hereinafter cited as. [S32]
- [S1042] Peter Wood, “re: Persse Family,” e-mail message to British and European Nobility Register, 2003 to 2021. Hereinafter cited as “re: Persse Family.”
- [S32] BLG2001. [S32]
- [S3508] S. Thomson, “email: Kirwan Family,” e-mail message to BENR, 16 January 2009 – 12 February 2010. Hereinafter cited as “email: Kirwan Family.”
- [S37] BP2003 See link for full details for this source. Hereinafter cited as. [S37]
Isabella Wallace1
Her married name became Macdowall.
Children of Isabella Wallace and Colonel William Macdowall, 1st of Castlesemple
- John Macdowall+2
- James Macdowall2 b. 1740
- Elizabeth Macdowall+2 b. Apr 1742, d. 12 Oct 1778
James Macdowall1 
He gained the rank of Captain in the King’s Own.1 He emigrated to West IndiesG.2 On 14 June 1766 he was seized with his brother of the lands of Kirriebroom.1
John Macdowall1
He succeeded his uncle Biggar (otherwise Wallace) of Woolmet.1
Child of John Macdowall and Mary Towers
- William Macdowall+2 b. 1770
Mary Towers1
Her married name became Macdowall.
Child of Mary Towers and John Macdowall
- William Macdowall+2 b. 1770
