Secret documents declassified on Friday by MI5 reveal in detail how in 1953 the UK under prime minister Winston Churchill overthrew the elected government of British Guiana – now Guyana – because he feared its leftwing leader and his American wife would lead the British colony into the arms of the Soviet Union.
The documents reveal how British spies kept up intense scrutiny on Cheddi Jagan and his wife Janet, who together founded the People's Progressive party (PPP) to campaign for workers' rights and independence from British rule for the sugar-producing colony in northern South America.
The UK had agreed a new constitution in the early 1950s which allowed British Guiana's political parties to participate in national elections and form a government, but maintained power in the hands of the British-appointed governor.
Christopher Andrew, MI5's official historian, said the files provide new details of the coup and "further evidence that MI5 played a more important part in British decolonisation than is often realised".
The Jagans – a US-educated former dentist and his wife, born Janet Rosenberg in Chicago – seem an unlikely threat.
But the 39 folders of files released by the National Archives are crammed full of tapped phone conversations, intercepted letters and accounts of physical surveillance over more than a decade.
In 1951, the year after the Jagans founded their party, an MI5 agent based on the nearby island of Trinidad described them as "something new in British Guiana politics".
"Both are able and intelligent and the mere fact that Janet Jagan is white, young and not unattractive in appearance lends considerable interest to her activities and those of her husband," he said.
To British authorities, the Jagans were a headache. To the Americans, they were a potential communist threat on America's doorstep.
MI5 concluded that their party was "not receiving any financial support from any communist organisation outside the country".
Nonetheless, amid worsening strikes and unrest, Britain grew unhappy with the Jagans' "disruptive antics".MORE