Rats leave Nick Griffin behind on the BNP's swiftly sinking ship

First the party's only other MEP quit – then the embattled leader found himself under investigation

Next weekend the remaining stalwarts of what was briefly Britain's fastest-growing party will gather in a Blackpool hotel room.

Access to the British National Party's annual conference, which is likely to be attended by about 100 activists, will be tightly controlled to prevent "spies" penetrating the gathering and relaying its deliberations to the outside world.

But it is hard to imagine that the mood of the meeting on the Golden Mile will be anything but sombre. Just three years after the far-right party achieved a remarkable electoral breakthrough, it now stands on the brink of collapse following internecine feuding, a slump in membership and the near-disappearance of elected BNP members.

It suffered a further grievous blow this week when open warfare between the BNP's two European MPs led to the resignation of the veteran activist Andrew Brons. His departure leaves Nick Griffin, the party's leader and now sole representative in Strasbourg, heading a rump of just four elected members.

Meanwhile, Mr Griffin suffered new embarrassment yesterday when it emerged police were investigating tweets he sent about a gay couple who won a landmark anti-discrimination court ruling after being refused a room by a guest-house owner.

In defiant interviews, the BNP leader, who had published the couple's address, insisted people have the "right to discriminate".

Although he may have relished the publicity, the episode marked a farcical new twist in the demise of the BNP, which some commentators trace back to Mr Griffin's disastrous appearance on BBC1's Question Time three years ago.

The days are over when his party had a strong presence on councils in Barking and Dagenham, Burnley, Calderdale, Epping Forest, Sandwell and Stoke-on-Trent, as well as a seat on the Greater London Assembly.

Mr Brons claimed this week that "80 or 90 per cent of the party's membership, activists and former officials have left it and disappeared in several different directions" and accused Mr Griffin of bearing the "heavy responsibility for having destroyed the party of which he is still nominally head".

Even if Mr Brons is exaggerating to make his case, the fact remains that the exodus has left the BNP broken-backed and struggling to maintain a profile in areas where it was once strongly represented. Last year it did not field a single candidate for Epping Forest Council, where it recently boasted seven councillors, and failed in June to contest a council by-election in its previous stronghold of Oldham.

Some defectors have quit Nationalist politics altogether, while others have left for some of the other far-right parties that were once overshadowed by the BNP.

They include the long-established National Front, which fielded 39 candidates in the last town hall elections, as well as Britain First, the British Freedom Party, the Democratic Nationalists, England First and the British People's Party.

In electoral terms, there is evidence that the space being vacated by the BNP is being partly filled by the UK Independence Party (although it strongly condemns racism) as well as the English Democrats, who are campaigning for an English Parliament. The English Defence League, the street protest movement against militant Islam, will also hold an appeal to some BNP activists.

Eddy Butler, a former BNP national elections officer who defected to the English Democrats, said: "At one point, Griffin had bounce and dynamism: even if you didn't approve of him, he could get people to follow him. But that is all gone now; if you see him, he is an empty shell."

In a new message on its website – presumably by Mr Griffin – the BNP acknowledges losing "experienced people", shedding members and complaining that "equipment was stolen or worn out and not replaced".

But it insists: "The British National Party is back as the only serious game in town. And now we are moving on and repairing the damage done by the troubles that are now behind us."

Far right splits: the factions

The current shake-up in the UK far right has been described as the movement's "last throw of the dice to form a viable political party". The English Democrats hold a relatively large membership and are hopeful of putting up the most candidates in the forthcoming local and European elections, as well as at least three police commissioner elections.

The English Defence League, meanwhile, is in a state of flux as its leader Stephen Yaxley-Lennon – aka Tommy Robinson – recovers from a failed attempt to form a political wing with the tiny British Freedom Party and his attempts to use the street movement as his own political vehicle. The British Freedom Party is concentrating its efforts on supporting Mr Yaxley-Lennon's cousin and EDL co-founder Kevin Carroll in his bid to become Police Commissioner in Bedfordshire.

A coterie of former Nick Griffin lieutenants are said to be setting up or joining small parties. Few – if any – have a chance of standing candidates.