Demonstrators demanding an end to Israeli airstrikes on Gaza hurled their shoes at the gates of Downing Street yesterday during a wave of global protests.
Riot police were also pelted with missiles and fireworks as about 5,000 pro-Palestinians descended on the Israeli Embassy in London in the evening.
Earlier in the day, around 12,000 people marched through the centre of the capital, including singer Annie Lennox, human rights campaigner Bianca Jagger and former mayor Ken Livingstone.
Elsewhere in Britain, 2,000 demonstrators took to the streets in Manchester and 500 braved the cold in Edinburgh.
Paris held the world's biggest protest, with 25,000 people showing up to condemn the Israeli offensive, which has killed at least 436 Palestinians since December 27th.
The death toll includes 75 children, according to Gaza medics. And almost 2,300 people have been wounded inside the territory.
Four Israelis have been killed by rocket attacks by Hamas, Islamist militants who took over Gaza three years ago.
In Britain, many people were angry at Gordon Brown refusal to condemn Israel's attacks.
Hundreds of protesters threw shoes at the iron gates of Downing Street residence, in the spirit of an Iraqi journalist who hurled his footware at President George Bush last year.
Around 1,000 pairs littered the streets outside Number 10 with demonstrating singing: ‘Shame on you, have my shoe.'
Zac Sommer, an 18-year-old British-Palestinian student from Essex, said: ‘Britain is quick to condemn Robert Mugabe, but where is the condemnation of Israel? Israel is killing hundreds of people.'
Also outside Downing Street, a firework exploded yards from the gates.
Later, around 5,000 protesters left the agreed marching route between Embankment and Trafalgar Square and headed for the Israeli Embassy in Kensington.
Hundreds of officers with truncheons and gas canisters locked shields during a stand-off outside the building.
Clash: Riot police deal with protesters trying to raid the Israeli Embassy in London
Focus point: Around 5,000 people went to the embassy after the march
Demonstrators taunted police, burned Israeli flags and threw sticks and stones at the diplomatic mission.
Others attempted unsuccessfully to storm the compound while officers were pelted with missiles and fireworks.
Ten people were arrested.
The demonstration in the capital was the biggest of at least 18 organised across the country.
Other rallies took place in Glasgow, Exeter, Bristol, Liverpool, Norwich, Hull, Tunbridge Wells, Leeds, Newcastle, Swansea, York, Caernarfon, Bradford and Sheffield.
Human rights advocate Bianca Jagger and singer Lennox have backed the protests, calling on American president-elect Barack Obama to speak up against the bombardment.
Speaking at a press conference in central London, Ms Jagger said: ‘I would like to make an appeal to president-elect Obama to speak up.
‘People throughout the world were hopeful when he was elected and we must appeal to him to ask for the immediate cessation of the bombardment of the civilian population in the Gaza Strip.'
Lennox spoke of her shock at watching scenes of the bombing on television.
She said: ‘A few days after Christmas I came downstairs, put the television on, and saw smoke pyres coming from buildings and I was shocked to the core because I was thinking as a mother and as a human being.
Madrid: Protesters burn an Israeli flag in the Spanish capital
Paris: Demonstrators burned cars after a march by 25,000 people
Berlin: Some 7,000 Palestinian supporters outside the city's cathedral
‘How was this going to be the solution to peace?'
She said the intervention from Bush blaming Hamas for starting the violence, had not helped the situation.
‘The problem is, from my perspective, they are pouring petrol onto the fire,' she said.
‘They have to sit down. This is a small window of opportunity just before things kick off.
‘For every one person killed in Gaza, they are creating 100 suicide bombers. It's not just about Gaza, it's about all of us.'
Liberal Democrat Sarah Teather said Israel's military response to the firing of Hamas rockets had been ‘disproportionate'.
‘Anyway, what Israel is doing is counter-productive. No terrorist organisation has ever been bombed into submission,' the Liberal Democrat MP said.
Police said 8,000 people demonstrated in the central French city of Lyon, 3,000 people protested in the southern city of Nice and 3,800 in Mulhouse in the east.
Two people were arrested as more than 1,000 marched through Amsterdam, condemning the Israeli airstrikes on Gaza and calling for a boycott of Israeli goods, police said.
Hundreds protested in Madrid, carrying signs saying ‘This is not a war but a genocide'.
More than 2,000 people also demonstrated in the Austrian city of Salzburg.