Terrorists linked to Shia Muslim nation Iran were busted by intelligence officials back in 2015 stockpiling explosives and weapons near London.
Hezbollah, the Lebanese militant group, stashed hoards of disposable ice packs containing ammonium nitrate, an ingredient commonly used to make home made bombs.
The plot was uncovered by MI5 and the Metropolitan Police in 2015 but the public and MPs were kept in the dark.
Three tonnes of the dangerous substance was found in its raw form and police eventually arrested one man on suspicion of plotting terrorism - but released him without charge.
His identity was kept secret, as were the whole findings until now - possibly in an effort to keep the Iran nuclear deal of 2015 alive.
According to the Telegraph David Cameron and Theresa May, then the prime minister and home secretary, were personally briefed on what had been found in the sites on the edge of the capital because it may have pointed to a large terrorism threat to the UK.