The whale spotted swimming up the Thames in central London has been unmasked as part of an undercover surveillance operation by terrorist organisation Al-Godiva.
Tourists spotted the creature and alerted marine wildlife groups who scrambled a crew to dive down and check that the whale was healthy and uninjured.
But on closer inspection it was discovered to have been a highly sophisticated mechanical submarine with little grinning Al-Godiva people inside.
Special government forces were brought in to capture the vessel and MI5 quickly sent out spoof reports confirming the whale's sightings and even elaborating on its species.
However, The Spoof's investigative team managed to unearth the truth and we have been able to exclusively interview one of the original diving team censured by MI5 agents.
For his own safety we are unable to print his real name, age, address or anything that he actually said.
George Wilmott, 54, from Wellington, Shropshire, said: "I couldn't believe my eyes. It's horrifying to think of the lengths that these evil little people will go to.
"When my five year old daughter heard about it she was so frightened she threw all her Flipper the Dolphin videos in the bin.
"She hasn't stopped crying and we only just managed to save our goldfish Blink from a flush with death."
An MI5 spokesperson, who officially doesn't exist, initially denied the allegations: "Reports of Al-Godiva infiltrating the Thames to blow up the Houses of Parliament is simply not true."
Yet when a member of The Spoof team contacted the Prime Minister's office the PM issued the following statement.
He said: "The idea of a mechanised Al-Godiva whale swimming up the Thames is truly horrifying and I want to reassure the public that I intend to immediately introduce a new bill in the next few days outlawing it.
"As a precautionary measure I also intend to introduce licenses for fish owners so that if indeed Al Godiva are behind this terrible incident, British-born fish cannot be so easily drawn into it.
"I am not at liberty to divulge details of the MI5 team who may or may not have been involved in the Thames incident as this could breach UK security.
"If there was such a horrifying incident, and I'm not saying there was, which MI5 agents could have prevented I assure you heads will roll.
"You may not get to know which heads will roll, if they do, because these agents need to work in total anonymity.
"However, I give you my word as PM that action will be taken, if the incident as has been described took place and if it is deemed necessary, at some point and you can trust me because I'm that kind of guy."
Leader of the opposition said he agreed with the PM that the Thames incident, if it is true, was truly horrifying and agreed that little Al-Godiva people ought to be ashamed of themselves.
But he added that his party has been pushing fish licences for the past five years and that had they been implemented this terrible incident might not have happened, if indeed it did.