Britain is proud of being one of few countries where police usually do not carry guns, and the sight of heavily armed counter-terrorism police officers in recent days is highly unusual one for many people.
While the image abroad of "bobbies on the beat" wearing tall hats and carrying little more than a truncheon and handcuffs is outdated, currently only 2,000 of the capital's 32,000 officers are armed.
"There will be more firearms officers available every day on the streets," London's Metropolitan Police Commissioner Bernard Hogan-Howe told LBC radio this week.
"What we don't want to do is to knee-jerk towards a new type of policing where everybody's armed," he added.
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British police are proud of their history of policing "by consent" -- the idea that police serve the people, not the state.
They say the principle would be tarnished by the sight of too many armed police officers.
"We are an unarmed force. We're proud of that. There are only probably four forces in the world that are unarmed, despite this huge city, despite this huge country," Hogan-Howe said.
Other countries in the world that have mostly unarmed police forces include Ireland, Norway and New Zealand.
Armed police are usually only deployed outside sensitive government buildings.
Since Friday, officers wearing body armour have been seen at football matches and transport hubs.
Still, police numbers have fallen sharply in recent years as part of a government-wide austerity drive, leading to fears London would struggle to cope with the kind of. Attacks that struck France on Friday.
"Once upon a time, you could get firearms support to somebody within 10 to 15 minutes," said a retired senior British police officer who declined to be named.