Scotland Yard have warned counter-terrorism units have been making arrests on a near daily basis amid a huge effort to contain the threat to the UK.
Activity by police and security services has been running at a high level for a number of years as they attempt to defend Britain against dangers ranging from lone wolf strikes to complex, mass-casualty plots.
Figures show there were 260 arrests for terrorism-related offences last year.
This was a slight fall compared to the previous year, but the number remained high compared with other recent years.
In March it was revealed authorities have thwarted 13 potential attacks in less than four years.
The official threat level for international terrorism has been at severe, indicating an attack is "highly likely", since 2014.
While Islamic State remains a major focus of the work of police and intelligence agencies, security officials have repeatedly stressed that the threat posed from al Qaida remains.
Counter-terrorism authorities are also handling a rising number of cases of far-right extremism.
Speaking on Friday following two separate counter-terrorism swoops in London the day earlier, Deputy Assistant Commissioner Neil Basu said: "I wanted to reassure the public that our increased activity to combat terrorism over the last two years continues, both by police and security services
"Activity continues around the clock to identify and stop these threats and we are making arrests on a near daily basis."
Although the pace of activity has been constant, Thursday's operations stood out from the relatively constant stream of arrests in recent years for different reasons.
Firstly, because of the location of the swoop in which a man was held in Whitehall.
He was arrested just yards from the scene of last month's deadly attack by Khalid Masood in Westminster.
Then in an unconnected operation armed officers launched a raid on an address in north London in which a woman was shot.
Although police conduct thousands of firearms operations every year, incidents in which officers discharge their weapons are extremely rare.