 While Harrison was working on Lancaster and Chester castles , he was also involved with domestic projects , four of them around Edinburgh in Scotland . The first consisted in making alterations to Gosford House for the 7th Earl of Wemyss . There is circumstantial evidence that he also designed the mausoleum in the grounds of the house , but a definite attribution cannot be made . This commission led , through personal contacts , for further work . The first was to build Kennet House near Clackmannan ( now demolished ) for Sir Thomas Dundas ; it was Harrison 's first major house . He then made extensions to Broomhall , a house near Dunfermline , for Thomas Bruce , 7th Earl of Elgin . Finally in Scotland , Harrison prepared plans for another new house , Colinton House near Edinburgh , for the banker Sir William Forbes . Following this , Harrison is credited with the design of Quernmore Park Hall , near Lancaster , for Charles Gibson , a house built between 1795 and 1798 . 
