Arthur Guinness started brewing ales from 1759 at the St. James’s Gate Brewery, Dublin. On 31 December 1759 he signed (up to) a 9,000 year lease at £45 per annum for the unused brewery. Ten years later, on 19 May 1769, Guinness first exported his ale: he shipped six-and-a-half barrels toGreat Britain.
“Stout” originally referred to a beer’s strength, but eventually shifted meaning toward body and colour.
Arthur Guinness started selling the dark beer porter in 1778. The first Guinness beers to use the term were Single Stout and Double Stout in the 1840s. Throughout the bulk of its history, Guinness produced ‘only three variations of a single beer type: porter or single stout, double or extra and foreign stout for export’.
Info gleaned from Wikipedia