Around 1.5 million are predicted to be enjoying sunny skies and the buzz of Europe's biggest street party, the Notting Hill Carnival.On Sunday, the annual colourful event began with Children's Day as hundreds of thousands turned out to view the parade of floats and flamboyantly-dressed performers.Police made 70 arrests, including two for attempted murder, and officers are maintaining a strong presence on Monday.This year's carnival is themed Set All Free, to commemorate the 200th anniversary of the abolition of the slave trade.Performers include London-born Allison Hinds, a hugely popular singer of Caribbean "soca" music.The carnival is also attracting health workers seeking to extend their campaign to keep the NHS public.Unison, the UK's largest health union, will bring two floats filled with brightly dressed staff to the parade.On Saturday, the showcase steel band competition - and complement to the carnival - "Panorama" attracted 10,000 people to London's Hyde Park.Forecasters say temperatures are set to reach 23C and the weather will remain warm long into the evening.© Independent Television News Limited 2007. All rights reserved.