Hundreds of thousands of revellers have descended on Notting Hill for the second day of carnival, which is being held in the shadow of Grenfell Tower.
At least 80 people died during the blaze at the west London block in June.
On Sunday, the carnival’s opening ceremony paid tribute to the victims and the sound systems were turned off for a minute’s silence.
The Met Police said there were 122 arrests on Sunday, a fall of about 20% on last year.
About a million people attended last year’s carnival, making it Europe’s biggest street festival.
Rooted in celebrating Afro-Caribbean culture and community cohesion, the event has taken on extra significance following the Grenfell tragedy.
The colourful floats pass within half a mile of the blackened tower and they are being encouraged to dip their music and walk respectably.
The entire procession will also pause for a second time for a minute’s silence.
Of the arrests, 54 were for drug offences, 15 for public order offences, eight for possession of a weapon and eight for sexual offences.
The London Ambulance Service said it had treated 344 patients during the first day of carnival – many for alcohol-related injuries.
London Mayor Sadiq Khan said on Sunday that although the 51st carnival took place in a “context of sadness and sorrow”, it was a celebration of London’s diversity.
A heavy police presence will mark the carnival route on Monday, with steel barriers and concrete blocks there to prevent a Barcelona-style terror incident as well as acid attacks.
At the scene: BBC reporter Dan Freedman
The police are putting the lower arrest figures possibly down to what they’re calling the Grenfell effect.
It’s added a degree of poignancy that has seen minute’s silences held here, and people dress in green as a tribute to those who lost their lives.
But I think most of that is far from most people’s minds; what most people are concentrating on is having a good time at carnival this year.
“The police, the security services – all of us – are working incredibly hard to make it a safe and successful carnival.
“We’ve got to make sure we keep our citizens and visitors, and those involved in the carnival safe, but also make sure we have a great carnival.”
Of the terrorism threat, one performer said: “Anything can happen to anyone anywhere and that’s what terrorists want you to do – to be inside and be afraid.
“You can’t do what they want you to do, you have to live your life so no, I’m not worried about it.”
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