Argentine President Cristina Fernandez de Kirchner has been left off the list, thanks to continued soreness over the Falklands war, and the objections of Thatcher's family.
After highlights from the list of invited heads of state, high-profile officials and other names were released Thursday, Downing Street confirmed Fernandez's absence was deliberate.
The late prime minister's children, Mark and Carol Thatcher, reportedly vetoed the presence of Fernandez or any other Argentine officials at the funeral.
The funeral plans involve the fanfare of a war hero's sendoff: More than 700 members of the armed forces will be involved in the service celebrating Thatcher's Falklands War successes.
Fernandez repeatedly tried to reopen the Falklands Islands disputes in recent months, over the objections of the Falkland Islanders themselves, who voted overwhelmingly in a referendum to remain under British control.
The British first took control the Falklands archipelago in 1833, and its 3,000 islands have since been inhabited by a tiny population of mostly English-speaking British citizens. In 1982, Argentina invaded, staking a claim to the islands they said were theirs by right, but Britain, under Thatcher's leadership, retook them in a counter-attack after just a few weeks.
All living British prime ministers and United States presidents are invited to the funeral, set for Wednesday, as well as heads of state from most nations with which Britain has "normal" relations.
Former U.S. first lady Nancy Reagan and former Soviet leader Mikhail Gorbachev will miss the funeral, both claiming they are unable to travel due to health problems.
Queen Elizabeth and Prince Philip have confirmed they will attend, unofficially elevating the service to the level of a state funeral, and Thatcher will receive full military honors.
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