Margaret Thatcher secretly considered the use of troops to break a strike by coal miners, according to newly released government papers.

Documents released by the National Archives at Kew, west London, show the extent of the planning by Mrs Thatcher's Conservative government for the decisive showdown with the miners which helped define her political legacy.

The papers show that ministers and officials repeatedly warned that a confrontation with the National Union of Mineworkers (NUM) and its leftwing leader, Arthur Scargill, was inevitable.

Mrs Thatcher, who had been a minister in Edward Heath's government in the 1970s when it was brought to its knees by a miners' strike was only too well aware of the stakes involved....