Stephen M. Studdert, former political adviser to Presidents Reagan and Bush, believes Great Britain and the world lost a great leader Thursday with the resignation of Margaret Thatcher.

"Margaret Thatcher was a very strong, highly principled leader whose every action was driven by a philosophical compass. She is one of my three political (non-American)heroes because she knows what she stands for and doesn't waver," said Stud-dert, who met with Thatcher several dozen times during her 11 years as prime minister, including a dinner last year at 10 Downing St. with Thatcher and Bush.

He lists his other two non-American political heroes as Indira Gandhi and Anwar Sadat.

Studdert's international strategic communications company, the Utah-based Studdert Group Ltd., serves as consultant to Britain's Conservative Party but has not been involved in Thatcher's bid to maintain power. He returned to his Highland, Utah County, home from London early Thursday where he was on business unrelated to the Thatcher resignation.

The political aide, who was with Bush and Thatcher on a number of occasions, said the two world leaders have enjoyed "a warm personal relationship, but it's clearly not as rooted as the Reagan-Thatcher relationship. It's very positive, but a different relationship, but very positive nonetheless," he said.

"Thatcher and Reagan were cut from the same political philosophy. They were close personal and professional friends," he said.

Studdert, who spoke with contacts in London Thursday morning after Thatcher resigned, said the prime minister returned from Paris and found a broad split in her Cabinet. She just didn't have the support to win, he said.

He tied Thatcher's fall to three factors - the perceived inequities of the unpopular poll tax, climbing unemployment and inflation, and European monetary issues.

"It's (the European monetary issue) an issue only because it triggered the resignation of Sir Geoffrey Howe (from Thatcher's Cabinet) and that provided the real door opener for (Thatcher challenger Michael) Heseltine," Studdert said.

He foresees the election of Hesel-tine, former defense minister, as the leader of the Conservative Party. He believes the entry of Chancellor of the Exchequer John Major, will take votes from challenger Foreign Secretary Douglas Hurd.