Complex sentence: He rented Lansdowne House in London until 1893, when he purchased a country estate at Cliveden-on-Thames in Taplow, Buckinghamshire from the Duke of Westminster.
Split into simpler sentences: He rented Lansdowne House in London until 1893. That year he purchased a country estate at Cliveden-on-Thames in Taplow, Buckinghamshire from the Duke of Westminster.