WASHINGTON – Margaret Thatcher and Ronald Reagan, two self-assured and firm-speaking conservatives, joined forces in the early 1980s and drastically changed the economic and political landscapes in both of their countries.

Their calls for more-austere government and lower taxes still resonate with ­conservatives on both sides of the Atlantic. And their side-by-side standing up to Soviet communism is credited by those of all political stripes as hastening the end of the Cold War.

The British prime minister and the U.S. president had the kind of personal bond that is extremely rare at such high levels of power.

She was the first and last White House State Dinner guest during Reagan's eight-year presidency. And when he died in 2004, at 93 after suffering for years with Alzheimer's disease, a frail Thatcher attended his state funeral.

"They had similar backgrounds and in some ways could understand what the other was experiencing," said Heather Conley, director of Europe programs for the Center for Strategic and International Studies in Washington.

"And they had unique ­solidarity. They were tough, they were single-minded in many ways. Some have argued that that lack of complexity was their shortcoming. But in some ways, their focus was their strength," Conley said.

Reagan and Thatcher forged a special friendship "from the very beginning, the first time they met," former First Lady Nancy Reagan said Monday.

"I loved it that she and Ronnie were as close as they were," she told Fox News.

Thatcher led Britain's Conservative Party to three election victories, governing from 1979 to 1990. Reagan was president from 1981 to 1989.

Both cut income taxes deeply and reined in national government spending. Both favored privatizing many government functions. Both stood up to organized labor. Both tackled inflation. Both were strong advocates of free markets and increased open international trade.

And both had a lasting — and controversial — impact on their own and ­opposing political parties in their respective nations.

Reagan's supply-side theories that lower taxes can stimulate growth was derided as "Reaganomics" by critics.

Even today, it is hard for Republicans to support any increase in taxes — a Reagan legacy that still makes it difficult for Democrats and Republicans to find common ground on tax legislation.

In Britain, Thatcher's policies were dubbed "Economic Thatcherism."

"Using deregulation and privatization, she restored Great Britain, once dismissed as the 'sick man of Europe,' to its position as a world power. Indeed, her policies led the way and inspired other nations to adopt similar reforms to boost their economies," Ed Feulner, former president of the conservative Heritage Foundation, wrote in a tribute.

"An intrepid warrior for freedom and human dignity, Prime Minister Thatcher stood with her 'noble friend,' President Ronald Reagan, to confront the Soviet empire when it was at its peak," ­Feulner added.

Thatcher's efforts in advancing conservative causes and programs in ­Britain may have strengthened Reagan's hand in selling his conservative agenda at home, and vice versa.

Conservatives at the time viewed the political victories of the two allies as part of a worldwide trend moving in their direction — a trend that has since run into a lot of bumps in the road.