William John never realised his full vision for Kingston Lacy. In 1841 he went into voluntary exile in Venice after he was charged for the second time with same-sex acts. At the time homosexual relationships between men were punishable by death.
During his exile, William John continued to compulsively collect and commission art, marble carvings and furniture. He sent them back to his siblings in Dorset with detailed instructions for their display. But he was never able to live at Kingston Lacy again, and in 1855 William John died whilst still in exile.