Astronuc said:
No, not really. That was Andropov and Gorbachev. It had nothing to do with Reagan and Thatcher. There involvement is a popular myth in some circles. Reagan and Thatcher (and their respective intelligence organizations and foreign affairs bureaus) were pretty much clueless, and they were caught off-guard by the events and subsequent collapse of the SU and Warsaw pact. It was a bit like a doctor being unaware of a cancer in a patient who deteriorates rapidly.
The myth is that the collapse "...had nothing to do with Reagan and Thatcher". This is not to say the pair were wholly responsible for the collapse of a deeply flawed and corrupt system, but they had a great deal to do with the timing.
Reagan, unlike his predecessors, set out with deliberate intent to collapse the SU: a sharp reduction of oil prices, aggressive stance of US Naval power, SDI, http://www.time.com/time/magazine/article/0,9171,159069,00.html, support for the Afghan resistance against the Soviet occupation, direct support for and mention of dissidents inside the SU, etc.
Edit:
Here's a video of Thatcher visiting communist Poland in 1988. While there, she demanded to see Solidarity leader Lech Walesa. See sailed into the shipyard in Gdansk, causing a near riot of shipyard workers who rallied to see her, and laid a wreath at the monument to shipyard workers killed in 1970 by Polish security forces.
http://www.pbs.org/wgbh/commandingheights/shared/video/qt/mini_p02_09_300.html
Whatever else one might say about this kind of engagement, it was directly opposed to the go-along policy of former PMs like Heath, Wilson, and Callaghan. Same goes for Reagan's predecessors. With the help of a Ford, a Carter, and perhaps a Heath instead of Reagan/Thatcher, then
Wojciech Jaruzelski's descendants might still be clinging to power in a communist Poland ala North Korea.
Lech Walesa's opinion of the impact of Thatcher on the Polish Solidarity movement:
Lech Walesa said:
Without this meeting there would have been *no* victory, that's for sure. There would have been delay, greater difficulties, or even our destruction