The frightening message read: "Pass on. Don't travel on the tubes tomorrow. Every single police officer in the Met has been called into work from 4am onwards, even people on holiday are being told to catch the next flight home.
"They think there's a terror threat and that it will happen on the tubes tomorrow around the West End area.
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"So don't go travelling on tubes!! It's better to be safe than sorry."
It finished: "Send this to all. If travel is a must, than walk with the Grace of God."
The text message came alongside news that UK security chiefs raised the threat level to “severe” from “substantial” following warnings that an attempted atrocity is “highly likely”.
Severe is the second highest of five levels, the highest being ‘critical’, and it means that Britain’s security forces believe a terrorist attack on home soil is highly likely.
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Unsurprisingly, Twitter was flooded with frightened Londoners asking for clarification on the message.
The hysteria prompted the commander of British Transport Police in London to post his own tweet, saying the situation was under control and the threat text had been established as a hoax.
The Metropolitan Police Service issued a one-line statement saying: "This rumour is completely untrue."
A Met spokesman added that it was not police policy to comment on hoaxes, adding: "We’re not discussing this any further."
It goes without saying that the text itself, while seemingly well-meaning, is an act of terrorism in itself.
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The definition of terrorism is, after all, 'the unofficial or unauthorised use of violence and intimidation in the pursuit of political aims.'
This hoax text has sparked terror in London - and, in doing so, it has achieved the primary aim of all terrorists.
However, while we should not stop our lives in the wake of a threat, many have said that, in raising our awareness of our surroundings, the hoax text may have achieved something good.
Meanwhile Home Secretary Theresa May has said the decision to raise the threat level is related to developments in Iraq and Syria, but that there was no information to suggest an attack was imminent.
Police have appealed to the public to help identify aspiring terrorists.