William Borthwick British politician (1879-1956) (1879–1956) Parents Letitia Mary Banks Thomas Borthwick Children Elinor Valerie Borthwick Brian Thomas Borthwick Margaret Ruth Borthwick William Jason Maxwell Borthwick Siblings Malcolm Algernon Borthwick Elinor Colston Borthwick James Alexander Borthwick Letitia Margaret Borthwick Sybil Mary Borthwick Thomas Borthwick, 1st Baron Whitburgh Partners Ruth Margery Rigby