William Whitelaw's loyalty was crucial to Margaret Thatcher during her early years in power - a fact acknowledged when she famously said: "Every prime minister needs a Willie."
Whitelaw was himself well-known for his turn of phrase, once accusing Harold Wilson's Labour of going round "stirring up apathy" during the 1970 election campaign.
He was Tory chairman under Ted Heath when Mrs Thatcher launched her bid to unseat him. Although he challenged her for the leadership, his subsequent declaration of loyalty earned him the post of deputy prime minister.
He was home secretary until the 1983 election, when he was made leader of the Lords. He died, aged 81, in 1999.