John Tremayne was born in London in 1825. He was a magistrate, deputy lieutenant for Devon and Cornwall and high sheriff of Cornwall in 1859. Later in his career he was an MP. He made changes to the gardens at Heligan, notably being involved in collecting and hybridising rhododendrons. He also developed the Jungle area and constructed the Ravine, an Alpine rockery. Along with his son, Jack, he began planning the Italian garden, which Jack completed after John Tremayne's death in 1901.