*L. Patrick Gray was summoned to the Oval Office and told: 'I don't think you can be Mr Nice Guy. Do like they did in the war.'
*The meeting was in February 1973 when Watergate was plunging the Nixon White House into crisis
* The FBI director had succeed J. Edgar Hoover and Nixon told him: 'There were no leaks when Hoover was there
*Disclosure is in new book One Man Against the World: The Tragedy of Richard Nixon, whose author accessed declassified documents