He was the son of Thomas Dundas and Bethia Baillie. He made his first fortune as Commissary General: supplying goods to the British Army during their campaigns against the Jacobites and in Flanders during the Seven Years' War, 1756-1763. He subsequently branched out into banking, property and was a major backer of the Forth and Clyde Canal which happened to run through his estate, centered on Kerse House, near Falkirk. He left his son an inheritance worth £900,000. Sir Lawrence was also a man of taste, elected a member of the Society of Dilettanti in 1750. , St. Andrew Square, Edinburgh He bought the Aske Estate, near Richmond in North Yorkshire in 1763 from Lord Holderness for £45,000 and proceeded to enlarge and remodel it in Palladian taste by the premier Yorkshire architect, John Carr, who also designed new stables. In 1768 he acquired a tavern "Peace and Plenty" on the land destined to become Edinburgh's New Town. This was shown on James Craig's plan as a potential site for a church, but Dundas's wealth and ownership of the site allowed him to design his own mansion here, somewhat off the grid of the New Town. This house, now Dundas House in St. Andrew Square, was designed by Sir William Chambers, became the headquarters of the Royal Bank of Scotland in 1825. The facade and later 1857 ceiling feature on the current designs of the banknotes issued by the Royal Bank. He purchased Leoni's grand house near London, Moor Park, for which he ordered a set of Gobelins tapestry hangings with medallions by François Boucher and a long suite of seat furniture to match, for which Robert Adam provided designs: they are among the earliest English neoclassical furniture. Other new furnishings, for Aske and for Sir Lawrence's magnificently appointed London house at 19 Arlington Street, were supplied by Thomas Chippendale, and Chippendale's rivals, the royal cabinet-makers William Vile and John Cobb, and Samuel Norman. A pair of marquetry commodes in the French taste by a French cabinet-maker working in London, Pierre Langlois, is at Aske. Capability Brown worked on the park at Aske and provided a design for a bridge. In the 1770s, Sir Lawrence turned to Robert Adam for further remodelling and designs for furnishings. The Aske estate included the pocket borough of Richmond, so Sir Lawrence was therefore able to appoint the Member of Parliament. Sir Lawrence married Margaret Bruce, and they had one son, Thomas Dundas. James Boswell described Dundas as "a comely jovial Scotch gentleman of good address but not bright parts... I liked him much". Dundas was a great collector of art. Long after his death Messrs Greenwood sold 116 of his paintings on 29-31 May 1794 from their room in Leicester Square. They included works by Cuyp, Murillo, Raphael, Rubens and Teniers. Some of the Murillos and perhaps other works would have been bought on commission by Dundas's friend John Blackwood. Sir Lawrence died in 1781 and is buried in the Dundas Mausoleum at Falkirk Old Parish Church where his wife Margaret and son Thomas eventually joined him.
