LONDON - Britain shed light on Mikhail Gorbachev's audacious bid to save the ailing Soviet Union on Friday, publishing previously secret documents showing his attempt to forge better ties with the West during the depths of the Cold War.

Gorbachev, whose reforms triggered the 1991 collapse of the Soviet Union, was in 1984 the main contender to succeed 73-year-old Konstantin Chernenko as Kremlin leader but was little known outside the Soviet Union when he visited London for his first major trip to Europe.

Invited by British Prime Minister Margaret Thatcher, Gorbachev's 1984 visit helped change the course of the Cold War by convincing the "Iron Lady" and her ally, US President Ronald Reagan, that the Soviet Union might soon be led by a man with whom the West could do business.

"I certainly found him a man one could do business with. I actually rather liked him," Thatcher told Reagan in a note marked confidential following hours of discussions with Gorbachev about the arms race of the Cold War.

"There is no doubt that he is completely loyal to the Soviet system but he is prepared to listen and have a genuine dialogue and make up his own mind," Thatcher told Reagan.

Within days of the meeting, Thatcher flew to Camp David to convince Reagan that Gorbachev would be different from Kremlin leaders such as Leonid Brezhnev, Yuri Andropov or Chernenko, who was so ill that he often missed politburo meetings.

The 1984 files show Thatcher juggling a strike by miners at home, and the high politics of reading the likely next leader of the West's most powerful foe.

Under a rule known in Britain as the 30-year rule, the around 500 files from the Cabinet Office and Prime Minister's Office in 1984 were deemed sensitive enough to be held in secret under the Public Records Act for 30 years.

Sensitive British documents were kept secret for half a century under rules brought in under Prime Minister Harold Macmillan just after World War II, but that was reduced to 30 year under Labour Prime Minister Harold Wilson.

The rule has been cut to 20 years in recent years, though extremely sensitive documents can be held back for longer with permission from the justice minister.