Britain's national terrorism threat level has been reduced from severe to substantial, Interior Minister Priti Patel said on Wednesday.
The change means an assault is considered likely rather than highly likely after two attacks, in October and November 2021.
But security chiefs at the Joint Terrorism Analysis Centre also warned people not to become complacent about any suspicious behaviour they see.
"JTAC judges that, despite these two attacks, the current nature and scale of the UK terrorist threat is consistent with the level of threat seen prior to the attacks,” Ms Patel said.
"The attacks in October and November 2021 reflect the complex, volatile and unpredictable nature of the terrorist threat in the UK.
"Any reduction in the threat level is positive but it must never make us complacent. Terrorism remains one of the most direct and immediate risks to our national security.
"The public should remain alert but not alarmed, and report any concerns they may have to the police.”
The threat level was increased to severe in November after an explosion outside a Liverpool hospital on Remembrance Sunday and the fatal stabbing of Southend West MP Sir David Amess at a constituency meeting at Leigh-on-Sea in Essex on October 15.
The "substantial" rating is the third highest in the system used to assess the terrorism threat, below "critical" and "severe" but above "low" and "moderate".
On November 14, a bomb was detonated outside Liverpool Women's Hospital, killing the bomber, Emad Al Swealmeen.
An inquest heard he bought 2,000 ball bearings and rented a "bomb-making factory" to make a device with "murderous intent".
Swealmeen died from the explosion and fire when the device detonated in a taxi, which was driven by David Perry.
Mr Perry managed to escape after the blast when his taxi pulled up outside the hospital shortly before 11am.
