Cape Town, South Africa ? The son of former British Prime Minister Margaret Thatcher pleaded guilty Thursday to unwittingly helping bankroll a botched coup plot in oil-rich Equatorial Guinea, and in exchange he received a fine, a suspended jail sentence and the right to rejoin his family in the United States.

Within hours of agreeing to the $506,000 fine, Sir Mark Thatcher checked in for a flight out of South Africa.

“There is no price too high for me pay to be reunited with my family, and I am sure all of you who are husbands and fathers will understand that,” Thatcher said outside court. Across the street, a poster reading “Save me mummy” hung from a window.

The bizarre coup plot drew mercenaries from elite British schools into an attempt to take over Africa’s third-largest oil producer.

Mark Thatcher admitted in the Cape High Court that he paid $275,000 in two installments last year to charter an Alouette III helicopter to be used in the takeover attempt. But he said in court documents that he was told it would be used for commercial purposes.

Lady Thatcher expressed relief Thursday that the case against her son was concluded.

“This has been a difficult time for all of the family,” she told Britain’s Press Assn. “Obviously I am delighted that it has been brought to an end.”

Mark Thatcher, who has lived in South Africa since 1995, was arrested Aug. 25 at his suburban Cape Town home and charged with violating this country’s anti-mercenary laws.

He also faces charges in Equatorial Guinea.