Before Donald Trump's retweets put Britain First on the world stage, ABC correspondent James Glenday spent a day with its leaders as they marched through an English town. This is his report:

When I first met Jayda Fransen and Paul Golding they were charismatic and friendly.

It wasn't the welcome I was expecting from the self-described Christian crusaders, who lead fringe far-right political party Britain First — an outfit known for its dislike of the media and one accused of inciting racial hatred.

"We want Islam banned in the UK," Ms Fransen told me, as she prepared to lead 150 supporters on a controversial march through the English town of Telford.

"We don't see why we should have to implement sharia law and sharia courts and have people wearing burkas, Islamic schools, mosques everywhere in our Christian country."

Members of Britain First claim Islamist terrorist attacks in Europe, Brexit and Donald Trump's election have helped make their views more mainstream.

Several believe the United Kingdom is headed for a holy war and most fear white British people will soon be a minority.

"That's the way things are going. Muslims are outbreeding native British 10 to one," Mr Golding said.

"They are going to be a majority within a few decades, it's going to lead to civil war.

"The bigger the Muslim population becomes the more terrorism, sharia law, the more problems that come along with them, Muslim grooming gangs that's why we're here today."

MP wants to list Britain First as terrorist organisation

On Facebook the group has a whopping 1.6 million followers, including a significant number of Australians. ( ABC News: James Glenday )

Many find those views very offensive and other right-wing groups, such as the UK Independence Party, have distanced themselves from the organisation.

But on Facebook the group has a whopping 1.6 million followers, including a significant number of Australians.

The page lures people in with patriotic memes but when you click through to the party's website there are also videos of their members "invading" halal slaughterhouses and mosques.

Mr Golding was recently jailed for breaching a court order banning him from entering mosques or encouraging others to do so, while in November Ms Fransen was convicted of religiously aggravated harassment for abusing a Muslim woman during a so-called "Christian patrol".

"I think there are individuals in Britain First that are out to subvert parliamentary democracy and to incite racial hatred," Labour MP Louise Haigh said.

Ms Haigh was a friend of Jo Cox — the politician who was murdered by a neo-Nazi sympathiser in June — and wants Parliament to debate listing the group as a terrorist organisation.

"We talk an awful lot about Islamic radicalism in this country whenever there is a terrorist attack … but that's very rarely the case when there's an extremist on the other side," she said.

"When Thomas Mair murdered Jo, he was described as a loner with mental health problems. Well, he wasn't. He was directly radicalised by the far-right movement in this country."

Fairly low membership

Britain First claims it isn't racist and doesn't do anything illegal. ( ABC News: James Glenday )

Despite its large social media presence, Britain First regularly struggles to get more than 150 people at public events.

Total membership is probably fairly low.

The Telford rally began when dozens of national flags started fluttering, Rule Britannia blared from portable speakers and the group — which features some men in homemade security uniforms — marched behind a large banner.

Within five minutes, there was trouble as Britain First came face-to-face with a counter-demonstration by anti-fascist protesters, who chanted, "Nazi scum off our streets."

More than 600 police just managed to keep the two groups separated but a brick was thrown, sticks and insults flew, a woman was injured and there were a few arrests.

Emboldened by the encounter, Ms Fransen and Mr Golding later delivered long-winded speeches filled with anti-Islam rhetoric where they mentioned driving Muslims into the desert and "hanging" liberal traitors.

In the middle of it all they paused briefly for the Lord's Prayer.

"I don't think Britain First are going to be directing terrorist action", said Paul Jackson — a lecturer from the University of Northampton who studies the far-right and extreme right in Britain.

"But they will legitimise views that then might lead somebody who wants to act violently to build on that culture."

'We are being targeted ferociously'

The British Government is closely monitoring the broader far-right movement.

It recently took the unprecedented step of banning neo-Nazi group National Action, and even though jihadis are the main focus of its flagship de-radicalisation program, far-right referrals are up 74 per cent.

"The far-right, or extreme-right movement in this country is probably not growing … but they are energised by recent world events," Dr Jackson said.

"I think we should see those figures as an increase in awareness in the potential problems posed by [the far-right], not an increase in overall activity."

For the record, Britain First claims it isn't racist and doesn't do anything illegal, though its star speaker for the rally, radical Polish priest Jacek Miedlar, was detained by border authorities en route and prevented from attending.

"We are being targeted ferociously and persecuted by the politically correct police authorities in this country," Mr Golding claimed when I asked why the group had so many encounters with the law.

"I've been arrested 10 times for confronting Islamic extremists."

It seems unlikely Britain First will be shut down but it isn't something that seems to particularly worry the group's leaders.

They claim they've got nothing to fear because God — the Christian one at least — is on their side.