Arthur has over forty years of experience designing gardens. He has contributed to the design and maintenance of a wide variety of Irish gardens, large and small, including Ashford, Dromoland and Glin Castles, Lyons Demesne, Coolmore Stud and all of Sheik Mahomed's Irish studfarms, Airfield House in Dundrum and Butler House in Kilkenny.
In 1999, Arthur transformed two derelict farm buildings and their accompanying land outside Abbeyleix, Co. Laois, into his own garden. Arthur shares Fruitlawn with artist Carol Booth and grows in the garden a wide selection of plants originally from his father, David Shackleton’s garden at Beech Park in Clonsilla. It has been called "enchanting" for its "billowing borders and quiet corners" by The Irish Garden Magazine, and has received visitors from around the world.