Lord Mountbatten came dangerously close to leading a cabal of industrialists, generals and tycoons plotting a coup against an elected Labour government, a new book reveals.

The 1968 plot was designed to replace Prime Minister Harold Wilson with a coalition government to bring the country together, during what Mountbatten and the conspirators regarded as a time of national crisis.

According to a new biography of Mountbatten, Prince Charles’s great uncle and mentor, it took the intervention of the Queen to persuade him to cut his ties with the plotters rather than acting against Wilson, his Cabinet and Parliament.

Drawing on contemporary diaries of the period, historian Andrew Lownie reveals for the first time the full extent of Mountbatten’s involvement in the plot.

It came amid growing social upheaval, industrial unrest and economic decline, with demonstrations in central London against the Vietnam war, student occupations and increased trade union militancy leading to a belief among some in the establishment that society was disintegrating.

The industrialist Cecil King, chairman of the publishing giant IPC, began gathering senior figures around him who wanted to act.

He believed Wilson, who had been elected in 1964 and again in 1966, should be replaced by a ‘national government’ led by the likes of the pre-war fascist leader Oswald Mosley or a figure of the stature of Lord Mountbatten, who had overseen the withdrawal of Britain from newly independent India in 1947 and had recently retired as Chief of the Defence Staff.