reply to post by Chonx
Doesn't mean anything. It's just because of the risk posed by unsavoury chaps from Yemen. There is no specific threat, just a heightened risk.
The new alert level means a terrorist attack is considered "highly likely". It had stood at substantial since July.
It is in response to the perceived increased threat from international terrorism following the failed Detroit airliner bombing on Christmas Day.
Mr Johnson stressed there was no intelligence to suggest a terrorist attack was imminent.
Source - BBC