Police officers are monitoring social media, internet forums and BlackBerry's messaging networks in the expectation that Margaret Thatcher's funeral procession next Wednesday will be targeted by protesters.
The possibility of demonstrations during the funeral has raised concerns that police may adopt the controversial tactic of making pre-emptive arrests.
Plans appear to be under way for different groups to demonstrate during the funeral, and to hold celebrations around the country on the same day.
Police concerns have been fuelled by the impromptu street parties which broke out on Monday evening in Belfast, Londonderry, Leeds, Bristol, Brixton, Liverpool and Glasgow. Some of the parties in England resulted in arrests after clashes with officers.
Police and security service planning for Baroness Thatcher's funeral has been under way for three-and-a-half years. Officers will probably line the route from the Houses of Parliament to St Paul's Cathedral to make sure that the cortege is not stopped.
The protests present a logistical headache for the Metropolitan Police, whose officers will have to make sure the procession is not disrupted while respecting the public's right to voice an opinion on one of Britain's most divisive politicians.
A Met spokesman said: "London's police, the MPS, City of London and British Transport Police are working together to deliver a security operation for Baroness Thatcher's funeral. Given the nature of the event, our operation will use of a range of appropriate tactics."
The Met's first large-scale challenge is likely to be handling anti-Thatcher protests this Saturday evening in Trafalgar Square – a part of London associated with the moment the former Prime Minister's power began to crumble as poll tax protests turned violent.
The Met has made "pre-emptive" arrests in recent years after gathering intelligence about high-profile demonstrations – most notably before the Royal Wedding in 2011. Scores of people were detained in its run-up.
Some of those arrested took their case to the High Court which ruled that, on the facts of the individual cases, the arrests were lawful. An appeal is set for this summer. At the time of the original case one of the arguments police used to justify the arrests was that they aimed to protect minority protesters from angry crowds.
Daniel, a 26-year-old from south London who was at Monday night's Brixton protest and is helping to organise something similar for Saturday evening, said: "There's never been an event with such a publicity run-up. At Brixton, the samba band and a sound system just turned up. Something similar will happen on Saturday."
He believed protests would only turn violent if the police tried to stop people voicing their opinion. "It would be unwise of the police to come down hard," he said. "Even a heavy police presence will provoke a reaction."
The legislation that allows for pre-emptive arrests is narrow and human rights lawyers have warned against any pre-funeral sweeps.
Michael Oswald, from Bhatt Murphy solicitors, which represented 15 people who were arrested during the Royal Wedding, said: "There must be a concern that the events that took place in Bristol and Brixton will be used by the police to justify the kind of tactics that were seen in the run-up to and during the Royal Wedding.
"Whatever one thinks about the rights and wrongs of protesting during a funeral, the law protects people's freedom to voice their opinions publicly in a peaceful manner."
Meanwhile crowds gathered in Belfast once again last night despite Sinn Fein's Martin McGuinness saying people should not celebrate the former leader's death.
The Deputy First Minister said on Twitter that people should "resist celebrating the death of Margaret Thatcher. She was not a peacemaker but it is a mistake to allow her death to poison our minds."
But despite his pleas, large crowds gathered on the Falls Road in west Belfast last night following her death on Monday.