Anyone who is in London when Margaret Thatcher's funeral takes place next Wednesday can expect it to "look very different" as a huge security operation swings into action, police said Friday.
Roads and Underground stations will be closed, police officers will be out in force, and members of the armed forces will line the route that the cortege will follow from Westminster to St. Paul's Cathedral.
With Queen Elizabeth II and many other dignitaries among the more than 2,000 guests, the "ceremonial"-style funeral for Britain's first female prime minister was bound to be a security headache.
The threat of possible demonstrations by anarchists and fears that dissident Irish Republicans may try to act have heightened concerns.
Thatcher was the target of a hotel bombing in Brighton by the Irish Republican Army in 1984, and two of her close colleagues were killed in attacks.
Her political legacy remains highly divisive, in part because many people blame her for creating soaring unemployment as she reduced or eliminated many government subsidies to businesses and took on unions.
Police were called out Monday in London's Brixton neighborhood, as well as in Bristol and Glasgow, after people gathered to "celebrate" the news of her death.
Anarchist groups are reportedly planning a big "party" Saturday in Trafalgar Square. The square, in the heart of London, was the scene of rioting in 1990 against a hugely unpopular levy brought in by Thatcher, the poll tax.
Reflecting the anger she still provokes among some people, sales of the "Wizard of Oz" song "Ding Dong the Witch is Dead" have skyrocketed this week. A Facebook campaign is encouraging people to buy the track to celebrate the former prime minister's death.
No violence, no crime
Commander Christine Jones of London's Metropolitan Police declined to comment on any specific groups that might pose a treat to public order.
But she told CNN that anyone planning to cause trouble on the day of the funeral can expect to be swiftly dealt with.
"We absolutely support people's lawful right to express themselves -- but it is a qualified right," she said. "That right is expunged if people decide that they are going to come to London to either commit acts of violence or crime. And we will deal with that."
The Metropolitan Police has called for anyone intending to hold a protest Wednesday to get in touch to discuss their plans.
Saturday's "party" in Trafalgar Square is not being viewed by police as a demonstration at present, she said. If people want to get together peacefully to share views, "there is no issue for the Met Police around that for public safety," she added.
Residents and visitors are urged to be aware that their freedom to move around may be affected.
"London is going to look very different on that day," said Jones.
"There will be parts of London that are not available. The transport system will look different. There will be various station closures and other changes to the London landscape which people may not be prepared for. And they may also want to be in a place where frankly we will not allow them to be."
The two-mile route along which Thatcher's coffin will be taken on a horse-drawn gun carriage passes some of London's most iconic landmarks, so tourists can expect to be among those affected.
'Our bread and butter'
The Met Police will be working with the City of London Police, who cover the capital's financial district, and the British Transport Police, as well as the country's intelligence agencies and other partners to keep the city safe, Jones said.
At the same time, she sought to downplay concerns that things may get out of hand despite the large scale of Wednesday's operation.
"We have a lot of experience in the Metropolitan Police -- in fact, really, this is our bread and butter," she said.
The threat level assessment from Britain's intelligence experts has not changed, she said.
Last year, policing efforts were dominated by the Diamond Jubilee, celebrating the queen's 60 years on the throne, and the London Olympics, which passed off peacefully. The wedding of Prince William and Catherine in April 2011 also involved a major policing operation.