About 28 years after British entertainer and comedian Bernard Cribbins’ novelty song “The Hole In The Ground” was released a team sent in by the Bulgarian defence ministry was “digging this hole” in Tsarichina, about 30 kilometres outside Sofia, although “it’s not there now, the ground’s all flat” but beneath the stone that marks where the work supposedly took place you probably won’t find a “bloke in a bowler hat”.

But, what you might find there is almost certainly one of the biggest mysteries to focus on the Balkan Mountains since Cribbins’ song reached number nine in the British charts.

The excavation work, codenamed “Operation Sun Ray”, began in December 1990 under a cloak of secrecy purportedly to search for the treasure horde of Tsar Samuil, ruler of the first Bulgarian Empire from 997-1014, but rumours quickly spread that it was really a search for a buried alien artefact or a mysterious entity believed to hold supernatural powers... FULL STORY