A mysterious group has been leading "anti-Muslim extremism" demonstrations around England this summer - who are they and what do they stand for?
The crowd of men surges forwards from the pub doors and is repelled by the police. The chant goes up in the heart of Birmingham's shopping centre.
"Muslim bombers off our streets, Muslim bombers off our streets!"
Then comes the response from about 50 equally mobilised people 200 yards away.
"Nazi scum out of Brum, Nazi scum out of Brum!"
Amid the increasingly chaotic scenes, someone throws a bottle - I don't see who - followed half-an-hour later by a rain of rubble from young Asian men who have turned up to join a stand-off.
This was Birmingham city centre last Saturday afternoon, in what is getting to be a monthly fixture. Over the summer the English Defence League has staged about half a dozen demonstrations around England.
In Birmingham, about 200 pretty fired-up young men came to the city to protest against "Islamic extremism and terrorism".
It looks like the bad old days of pitched battles between skinheads and the Anti Nazi League.
At one point, the English Defence League's supporters charge down a side-street after the various sides goad each other to "come and have a go".
The police floor the most troublesome, including one man I speak to as he sits on the kerb, handcuffed.
"I'm from Birmingham, mate, I live here. I'm sick of Muslim extremists slagging down our soldiers, thinking they can build up their mosques and call us scum -"
"Oi! I don't like racist people," comes the response from another Brummie, passing by.
"Sit down! Sit down!" shouts a police officer.
"I've got a mate who's just come back from Afghanistan - he's in the Army - he's an Asian man," continues the bystander. "You're giving me a bad name as a white person."
The scenes are pretty terrifying for those who've popped out for a coffee in a New Street cafe. But despite 90 arrests (not all of whom were EDL supporters), this isn't anything that the city's police are unable to contain.
Genesis of protest
But the emergence of the English Defence League is worrying many people - not least because it's very difficult to work out who they are.
The BBC has learned that four specialist national police units are investigating the EDL, including detectives with a background in watching hooliganism - but also extreme violence and terrorism. Those units are building up a picture of what the organisation is doing with the help of the British Transport Police and constabularies who have policed the demonstrations to date.
This week the BBC secured exclusive interviews with some of the organisation's leaders.
At a building site north of London, we meet "Tommy". He won't give his real name because he says he will be targeted by extremists.
Joining Tommy is an older man called Alan, from London. Later, a young man from Luton turns up with a mixed-race teenager from north London, who Tommy says is the head of the "youth wing".
"There are town centres now that are plagued by Islamic extremists," he says. "There are women who don't want to go shopping because there are 20 men in long Islamic dress shouting anti-British stuff and calling for a jihad and stirring up religious and racial hatred. Those are our town centres, and we want them back.
"We want them back, not from the Muslims, but from the jihadist extremists that are operating in the Muslim communities. And the Muslim communities need to deal with their extremists.
"They need to drive them out - we have had enough of it."
The English Defence League emerged from the angry scenes in Luton last March when a group of Muslims protested as the Royal Anglian Regiment paraded through the town on its return from Afghanistan.
When a counter-demonstration under the name of United People of Luton led to arrests, local football supporters decided something should be done.
They found common cause with other "soccer casuals" and "firms" associated with major clubs. The chatter concluded that this was a national problem and they had to put aside club rivalries.
Things really took off after the same Islamist group "converted" an 11-year-old boy in Birmingham city centre in June. That incident caused a minor tabloid furore - but a greater reaction on the net, particularly on websites and forums associated with football violence and far-right activity.
By the summer there were English Defence League "divisions" run by football supporters in Luton, north London, Bristol, Portsmouth and Southampton, Derby, Cardiff and the West Midlands.
The EDL turned its attention to Birmingham in August with a march, but found itself outmanoeuvred by anti-racist protest groups in ugly scenes that led to 35 arrests. A similar march planned for Luton was banned.
The EDL has now organised around 15 principal figures loosely based around the football firms providing the most support. Not all of those involved are from a football background, and many of the men have yet to meet each other face-to-face. But they are mobilising for each other on trust, using websites including Facebook and YouTube.
The British National Party has distanced itself from the EDL, but anti-racism campaigners have named party activists they have photographed at demonstrations. They add that some demos have included people with a record of football violence.
Each demonstration has led to confrontations. But leaders like Tommy are appealing for demonstrators to avoid drink because they don't want to be written off as racist thugs.
In Birmingham last week, the BBC filmed black and white men alongside each other on EDL's lines.
So if it's not exclusively white, is it just a cover for a wider Islamophobia?
"People aren't against Islam, they aren't against anything else other than the funders of terrorism, the sworn enemies of Britain," says Tommy.
"For 10-15 years these groups have gone unchallenged in our towns and cities. Those days have gone now. We will challenge them. Wherever there are terrorists, we will be there."
Nick Lowles is the editor of Searchlight, which campaigns against far-right extremists.
He says that the English Defence League should not be written off because it poses two risks.
"What we are seeing is the formation of a street army, people who will travel around the country to fight," he says.
"Into this mix you can get [far-right] organisations winding them up - let's go here or there, here's some money - giving them some organisational support, that kind of thing.
"But the risk is what happens if they go into areas where there are existing tensions. All those places are potential flashpoints. That's the explosive mix that we have got here.
"I'm not saying that every leader of the EDL is a fascist or hardcore racist but as you have seen with the signs, chanting and actions, it's anti-Muslim - and that's incitement."
Born and bred
Muslim groups are increasingly concerned about the EDL - and they say it's blatantly Islamophobic. In Birmingham, young Muslim men vow to "defend" the city if the EDL turns up again.
"This is our home - where exactly do they want us to go, we were born here," says Amjad, a 19-year-old from Alum Rock. "These guys are coming here because they hate us. Well, I'm not going to stand for it, and the police are wrong, the council are wrong, to let this go on."
As the sun dips beneath the horizon on our building site, Tommy gets fidgety. He wants to leave for the England-Croatia kick-off.
We put Nick Lowles' accusations - and the fears of Muslims - to Tommy. We also cited EDL supporters' own words, including a video on YouTube describing them as "the most organised and ruthless street army in the country".
Tommy says: "We know that the Muslim community may come under some heat from this, but the Muslim community of Britain needs to understand that our community is under heat from these fanatical jihadists.
"The hatred is affecting us. It's a disease sweeping the country, and it needs stopping."