Following work for Samuel Madden and the Earl of Milltown, Barret started to produce paintings of Irish landscapes. These portrayed the actual landscape and not capriccio scenery. This was a natural progression from his previous idealised Italianate scenery. Barret is particularly associated with Edward Wingfield who in 1751 became Viscount Powerscourt. Wingfield owned Powerscourt House and extensive estates to the south of Dublin in County Wicklow. These included the scenic river Dargle with its craggy red rocks and impressive Powerscourt Waterfall that is the second highest in Ireland. Scenery on the Dargle often figures in Barret's surviving oil paintings and he also painted at Avoca in the south of County Wicklow.