Lord Mayor's show in London marks Paris attacks
The Lord Mayor's Show went ahead in London with flags at half mast, fireworks cancelled and a two-minute silence following the attacks in Paris.
City of London Police said a "proportional policing operation" was in place. Armed officers were present.
The new Lord Mayor Jeffrey Mountevans led the two-minute silence marking the Paris attacks.
This year's events marked the 800th anniversary of the role of lord mayor of the City of London.
Organisers cancelled the fireworks, saying: "It is time for a show of solidarity with the victims of an atrocious terrorist attack and not a time for celebrations."
Instead, Tower Bridge was lit up in the colours of the French flag from 16:30 GMT "as a mark of respect", they said.
The Library of Birmingham was also lit up in the red, white and blue colours of the Tricolore, as was Blackpool Tower, Portsmouth's Spinnaker Tower, the London Eye, the National Gallery, Norwich City Hall and Leeds Arena.
Coventry Cathedral was also lit up as part of a ceremony to mark the 75th anniversary of the Luftwaffe bombing raid on the city.
In central London two vigils took place at Trafalgar Square - one earlier in the day and one in the evening. Both were organised by French residents in London.
At the evening vigil hundreds of people held their phones aloft, the light of their screens illuminating the darkness, or lit candles.
London has about 300,000 French residents, which has led some people to suggest that it is France's six biggest city in terms of population.
A similar vigil also took place in Liverpool attended by French nationals and students.
Hanna Corbett, a Nottingham University student from St Albans has spoken about the "nightmare" of being caught up in the attack on the Bataclan concert hall in Paris.
And the London School of Economics has said one of its former students, Valentin Ribet, who graduated in International Business Law in 2014, was one of those who died on Friday night.
Secondary school students from Croydon, south London, who were among those in Paris at the time of the attacks have arrived home.
Pupils and teachers from Riddlesdeown Collegiate cut short their trip and sobbed as they arrived back at St Pancras Station amid tight security at the terminal.
"It's been obviously very worrying for us and for our parents," said principal Soumick Dey. "It's lovely to see them all safe back here now."
At Gatwick Airport a French man was arrested and the North Terminal was evacuated as a precautionary measure after a firearm was found.
Mayor of London Boris Johnson said: "We regard Paris as our sister city, a place for which we have deep reserves of love and admiration and respect.
"We are two capitals united in our values - democratic freedom, openness and tolerance.
"The people who launched the attacks last night have no such values. They wish to undermine the things we hold most precious."
The Lord Mayor's Show was the first public engagement for the new Lord Mayor, who is a maritime expert and the 688th mayor to fill the position, representing the city in financial and business matters across the world.