There was nothing accidental about the Real IRA's target nor its timing. Just hours before Martin McGuinness's historic first appearance at the British Conservative Party conference, the paramilitary group bombed a bank in Derry.

"It was entirely appropriate that Martin McGuinness's condemnation of the IRA operation came from the Tory conference," a Real IRA spokesman told the Sunday Tribune.

"The man who once bombed Derry into the ground is now on the side of bankers and big business. His sentiments are in keeping with those of his Tory friends. The contrast between McGuinness and those still committed to the republican struggle couldn't have been greater."

The PSNI has said the bombers originally had another target and the bomb was abandoned at the Ulster Bank due to a heavy police presence. The Real IRA denies this, insisting the bank was the intended target. Following MI5's warnings about the possibility of dissident republican attacks in Britain, the Derry bomb caused a furore. But the threat is being exaggerated. Had the dissidents bombed the Tory conference, or the City of London, the security services would have something to worry about.

But there are no signs yet that dissidents have the capacity to hit Britain. They have also had mixed results with explosives at home. The Real IRA bomb in Derry followed a similarly 'successful' attack on Newry courthouse in February. However, a van bomb failed to detonate outside Aughnacloy police station in Co Tyrone in June.

Despite media hype, 18 months after the murder of two British soldiers at Massereene and that of Constable Stephen Carroll, the dissidents haven't inflicted any fatalities on the security forces. The Real IRA and Óglaigh na hÉireann (ONH), a Real IRA splinter group, are the most active groups. ONH came close to killing a police officer in January. Peadar Heffron lost a leg after a bomb exploded under his car. The Real IRA spokesman makes no predictions of an intensive campaign to force a British withdrawal. The group's short-term strategy is 'hit-and-run' sporadic attacks aimed at showing that the North still isn't a normal society.

The dissidents' 'success' is their continued existence. The Derry bomb came days after Bill Clinton visited the city. Fifteen years ago he had declared physical force republicans "yesterday's men".

Their resilience has surprised many. And it's their potential which causes most concern. The Real IRA is opting for slow, steady growth rather than burning itself out by attempting spectaculars.

Derry is its strongest area. Retrospectively, naming it as UK City of Culture 2013 could prove foolish. For dissidents, the accolade is the proverbial red rag to a bull. Gary Donnelly (39) is a prominent member of the 32 County Sovereignty Movement in Derry. Security sources allege it's the Real IRA's political wing, a claim the group denies.

According to Donnelly, today's militant republicans pay as much attention to Martin McGuinness's condemnation of the Real IRA bomb as the Provisionals did to SDLP condemnation during their campaign. "McGuinness has predicted a backlash against 'dissidents'. He is out of touch with the reality on the ground," he said.

"The Sovereignty Movement had 50 people delivering our news sheet, Beir Bua, in Derry this week. There was no backlash. There isn't massive support for IRA attacks among nationalists, it's minority support. But armed struggle has never been popular. While plenty of people voted Sinn Féin, only a minority supported the Provisional IRA campaign."

Ciaran Boyle (25) is one of a growing number of young people involved with the Sovereignty Movement. How does he view the bank bomb? "As a Derry man unemployed for two years, I blame the bankers for the recession. An attack on a British bank is a good thing. It's even popular with my friends who aren't republican. Nobody cares about a bank."

The PSNI has announced a security clampdown on dissidents. According to Boyle, "Irish history shows that will lead to more support for republicans. They can have all the clamp-downs and condemnations they want. We are here, we have a voice, and our voice will be heard."

Nathan Hastings (17), another Sovereignty Movement recruit, is at grammar school studying for his 'A' Levels. "Bombing banks hits Britain where it hurts," he said. "Britain cares more about money and property than about the lives of its soldiers, whom it sees as cannon fodder. I supported the attack 100% and hope there will be more." The Sovereignty Movement members were speaking personally and not on behalf of the organisation.

Former civil rights leader Eamonn McCann said the dissident campaign is very unpopular: "People don't see it in terms of bombing a bank. They see traffic disruption and residents, many elderly, being moved from their homes.

"But it's pointless demonising the dissidents as gangsters with no politics. There are clear parallels between their campaign and the Provos'. The Provos were wrong then and the dissidents are wrong now. Their campaign will bring death and misery to all involved." McCann is organising a trade union rally on Friday against dissident attacks.

Thomas 'Dixie' Elliot, a former IRA prisoner who served 12 years for the attempted murder of a British soldier, opposes Sinn Féin's political direction and dissident violence: "They have no strategy. They're mimicking failed Provisional IRA tactics. They want to bring us back to the 1970s and '80s.

"Afghan and Iraqi guerrilla armies are hitting the Brits with more firepower and killing more in a day than all the Irish physical force groups put together have done since their formation. If the deaths in Iraq and Afghanistan have little impact on the British, a very low-level campaign in Ireland will have none whatsoever." Elliot believes the dissidents are "a ticking time-bomb to disaster in terms of the death of IRA volunteers or civilians".

The home of former internee Mickey Donnelly shook in Monday's explosion but he won't condemn the attack: "The dissidents actually aren't as ruthless as the Provos were with commercial targets. In 1977, the IRA in Derry killed the managing director of the Du Pont plant, Jeffrey Agate. They claimed he was 'propping up the six-county economy'. The man who killed Agate has been running around Derry all week condemning the dissidents. You can't take that seriously."