[1] He made his first fortune as Commissary General: supplying goods to the British Army during the Jacobite rising of 1745 and the Seven Years' War.

Dundas subsequently branched out into banking, property (he developed Grangemouth in 1777) and was a major backer of the Forth and Clyde Canal which happened to run through his estate, centred on Kerse House,[2] near Falkirk.

[6][7] He purchased Giacomo 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.

The Aske estate included the pocket borough of Richmond, so Sir Lawrence was, therefore, able to appoint the Member of Parliament.

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.