Britain First is facing a potentially costly investigation by police into its emblem which appears emblazoned on all merchandise by the far-right party.

Scotland Yard has announced is it probing whether the party has illegally ripped off the Royal family's St Edward's Crown to use in its own badge.

The contentious detail in question is the gold lion on prominent display in the logo, against a Union Jack background, which is ringed by the extremist group's motto. But the crest belongs to the Royal family, meaning it cannot be used without Crown consent.

Being found guilty of infringing crown copyright would almost certainly deal a blow to the extremist group's pocket, by meaning almost none of its merchandise can be sold legally.

That would be problematic for Britain First, which pays more attention to selling branded gear than most other groups of its ilk – and even mainstream political parties.

Party leader Paul Golding was defiant and insisted Britain First would carry on using the St Edward's Crown.

Far-right watcher Matthew Collins told IBTimes UK making money is a top priority for the group.

"They have a very active online presence. They are an organisation which is continually bleeding its membership dry and are most interested in selling badges, flags and t-shirts," Collins said.

Britain First makes relatively little from members' subscriptions because the membership base is comparatively tiny, he added. Earlier this year, Golding told the BBC the party had 6,000 members, but Collins cast doubt on the figure. "It's more like 1,000. Britain First is not experiencing growth," he said.

So with no secure subscriber base to rely upon, selling heavily branded merchandise online becomes more important. The extremist group sports a well-stocked online shop with a startling array of clothes and jewellery to choose from, including t-shirts, jumpers and baseball caps.

The party has amassed more than half a milllion 'likes' on Facebook, which means there are plenty of web users being directed from the group's social media page to its official website, where the shop is prominently displayed.

Receipts from sales help fund the Britain First, which has gained notoriety for carrying out mosque invasions and threatening to bury a pig on the site of a proposed mosque in Birmingham.

However, much of the online support is from so-called 'keyboard warriors' - people who never take part in real-world events by Britain First - said Collins.

"It does not make them a big group," said Collins. "The BNP had the same and it is now dead. Britain First has not been able to translate the online support into boots on the street. There no indication it is growing at all, in fact it is in decline."

Announcing police are investigating whether the group's use of St Edward's Crown is illegal, a Metropolitan Police spokesman said: " We can confirm we are investigating criminal allegations in relation to the unauthorised use of the St Edward's Crown, under S99 Trade Marks Act 1994, S12 Trade Descriptions Act 1968 and Regulation 3 Consumer Protection from Unfair Trading Regulations 2008."

Golding hit back by claiming police wrongfully leaked details of the investigation to the press before informing the group.

"I think it's a politically motivated and biased piece of political theatre. We have been using it for four years, so we wish them the best in their quest to score points. We aren't fazed or fussed," he told IBTimes UK.