Potter had been a disciple of the land conservation and preservation ideals of her long-time friend and mentor, Canon Hardwicke Rawnsley, the first secretary and founding member of the National Trust.[79] According to the National Trust, "she supported the efforts of the National Trust to preserve not just the places of extraordinary beauty but also those heads of valleys and low grazing lands that would be irreparably ruined by development." Potter was also an authority on the traditional Lakeland crafts and period furniture,[80] as well as local stonework. She restored and preserved the farms that she bought or managed, making sure that each farm house had in it a piece of antique Lakeland furniture. Potter was interested in preserving not only the Herdwick sheep but also the way of life of fell farming.[81] In 1930 the Heelises became partners with the National Trust in buying and managing the fell farms included in the large Monk Coniston Estate.[82]
The estate was composed of many farms spread over a wide area of north-western Lancashire, including the Tarn Hows. Potter was the de facto estate manager for the Trust for seven years until the National Trust could afford to repurchase most of the property from her. Potter's stewardship of these farms earned her full regard, but she was not without her critics, not the least of which were her contemporaries who felt she used her wealth and the position of her husband to acquire properties in advance of their being made public. She was notable in observing the problems of afforestation, preserving the intact grazing lands, and husbanding the quarries and timber on these farms. All her farms were stocked with Herdwick sheep and frequently with Galloway cattle.[83]
