The Douglas family of the second creation are the same of the same lineage as the Marquesses of Queensberry (note the appearance of the middle name Sholto in both families) and are also related to the later Earls of Home.
Llyn Conwy was at one time owned and looked after by Lord Penrhyn, who kept the lake well stocked.
Baron | William Cecil, 1st Baron Burghley | baron | Sacha Baron Cohen | Joseph Lister, 1st Baron Lister | Joey Baron | Robert Baden-Powell, 1st Baron Baden-Powell | Henry Brougham, 1st Baron Brougham and Vaux | Guy Carleton, 1st Baron Dorchester | William Wallace, Baron Wallace of Saltaire | William Tyssen-Amherst, 1st Baron Amherst of Hackney | James Mackay, Baron Mackay of Clashfern | Hercules Robinson, 1st Baron Rosmead | George Brydges Rodney, 1st Baron Rodney | Beechcraft Baron | Thomas Seymour, 1st Baron Seymour of Sudeley | Thomas Denman, 1st Baron Denman | Stuart Rendel, 1st Baron Rendel | Norman Foster, Baron Foster of Thames Bank | John Moore-Brabazon, 1st Baron Brabazon of Tara | Charles Cochrane-Baillie, 2nd Baron Lamington | Charles Calvert, 5th Baron Baltimore | Benedict Calvert, 4th Baron Baltimore | Baron Hans Heinrich Thyssen-Bornemisza | William Ponsonby, 1st Baron Ponsonby | Walter Rothschild, 2nd Baron Rothschild | Sidney Herbert, 1st Baron Herbert of Lea | Robert Napier, 1st Baron Napier of Magdala | Martin Conway, 1st Baron Conway of Allington | John Reith, 1st Baron Reith |
The quarry was first developed in the 1770s by Richard Pennant, later Baron Penrhyn although it is likely that small-scale slate extraction on the site began considerably earlier.
In 1765 Anne Susanna married the other heir to the Penrhyn estate, Richard Pennant, who later became the 1st Baron Penrhyn.