By Emma Griffiths
BBC News Online
Clouds of orange smoke hung over Parliament Square on Wednesday as smoke bombs and fireworks disrupted what had been a peaceful protest by huntspeople from across England and Wales.
Protesters had some angry messages for the prime minister
While protesters were hemmed in by riot police outside, five got into the Commons chamber, disrupting MPs as they debated a Bill to ban hunting with dogs in England and Wales.
Long before trouble erupted, police vans full of officers were on standby, but riot police moved in after a small section of the crowd tried to break the police cordon.
Many protesters were not surprised that trouble had flared up.
Aggie Chapman, a protester from Peterborough, said: "There's such a strong feeling here because the government refused to listen to us - we have been protesting for years peacefully.
"This is an unjust law which is making ordinary citizens into criminals."
Huntspeople were in rebellious mood as the day began.
Some held official Countryside Alliance posters, others had made their own placards bearing defiant hand-written messages to the prime minister.
"Banning Easy, Enforcement Impossible - That's A Promise" and "Tally Ho Tony, We're Off Hunting" suggested many would not see a ban as the final word.
Particularly popular among the younger protesters were T-shirts which had hijacked French Connection's controversial slogan to read "FCUK yer ban".
"These people are very angry," said Davina Morley, 53, from Yorkshire, who has been hunting all her life.
"We are not thugs, we are not football hooligans - we are ordinary, law-abiding folk. We are very peaceful people, but we hope to show that we care."
Alongside adults in waxed jackets and Wellington boots and elderly men in flat caps were many youngsters for whom hunting is part of family life.
Many protesters said they would continue hunting regardless and few seemed convinced that the move was about animal welfare rather than party politics.
"I fear it is being done for good, old-fashioned misconceived ideas about the sort of people who go hunting," said Luke Annaly, from Banbury, Oxfordshire.
"People have come from all over the country and all sections of society. It's no longer a privileged exclusive activity."
Edward Trotter, 30, who lives in London but is moving to Edinburgh, said: "I haven't been hunting for quite a while, but I intend to keep going for the next five or ten years - or 50 years if I can help it."
Extra police had been drafted in and stood in groups at traffic lights and other crossings lining the route from Westminster Tube station.
By 1045 BST their crowd control skills were already being put to the test by the increasing numbers of new arrivals trying to cross heavy traffic in Parliament Square.
Rachel Hanks and Tim Edwards face losing their home and livelihood
By 1300 BST Scotland Yard was reporting up to 10,000 demonstrators in the square and "no problems".
But the Countryside Alliance had its own "evidence gatherers" at the scene, to record collisions between protesters and mounted police.
In one corner of the square, as protesters starting sounding hunting horns, members of the South Dorset Hunt were waiting for the rally to begin.
Among them was Tim Edwards, who had been up since 0430 BST seeing to the hounds before he, his partner and his 12-year-old daughter drove to London.
A kennel huntsman for 20 years, Mr Edwards and his family live in tied accommodation, so he faces losing his home and his livelihood.
"It's all I know," he told BBC News Online.
"Once they ban blood sports, I won't have anything else to do."
Stud groom Charles Vickers, 38, also lives in tied accommodation with his partner Alison Kinge, 30.
As jobs with horses are generally low paid, they would be unable to buy their own homes and would struggle to afford rent, Ms Kinge, also a groom, said.
But Mr Vickers said whatever the decision, it was not the end for hunting.
"This is only the start," he said.
"We will be here every week if that's what it takes - we will never stop it. It's both our jobs and our livelihood, it's a way of life, friends, a community - everything."