Today the International Commission of Inquiry into the case of the Miami Five kicks off in London, although one of the five to have been released, René González, has shockingly been refused entry to this country - probably to appease the US.

The US government makes a habit of being out on a limb when it comes to its relations with Cuba. For 22 years it has consistently ignored a UN vote by the rest of world against its inhumane policy of blockade.

But even the US, a country notoriously thick-skinned and belligerent when it comes to listening to international opinion, would be ill-advised to ignore the mounting pressure for change.

Internationally and internally, its failed policy is being questioned from the most unlikely places.

This month a nationwide poll by the Atlantic Council showed that more US citizens than ever before favour normalising relations and engagement with Cuba. What is most notable is that the poll's findings remain the same among sample groups of Republicans and Cuban-Americans, groups traditionally seen as being pro-blockade hardliners.

And surely the irony is not lost in Congress when increasingly it is US politicians who lament the damage that the blockade is causing the US economy and its people who are unable to benefit from Cuban trade or medical innovations.

In an op-ed piece in the Miami Herald entitled Time For A New Policy On Cuba, US Senators Patrick Leahy and Jeff Flake noted that "a majority of Americans, including Cuban-Americans, want to change course" and "so do we."

In much of the US media the tone is beginning to change too. Last week a Los Angeles Times editorial, Cross Cuba Off the Black List, called for Cuba to be taken off the state-sponsor-of-terror list.

Britain's Financial Times called for the same in a recent editorial: Embargo Is Embarrassing, Anachronistic - And Has Failed.

The world's media has by no means had a change of heart on Cuba. It still peddles misinformation from the US State Department and right-wing exile groups.

But its line on US government policy towards the island is beginning to shift from ridiculous cold war propaganda to a more reasoned and sensible line.

Even the closest US allies are cranking up the pressure. At the Organisation of American States (OAS) meeting last year Colombia's President Manuel Santos, Barack Obama's best friend in Latin America, sided with other member countries to give Obama the ultimatum that unless Cuba is included in the 2015 OAS regional meeting the summit will not go ahead.

Back home, Britain itself has already signed a bilateral co-operation agreement with the island and the European Union is currently in discussions to end its "common position" which has been a de facto mini-blockade hanging on to the coat-tails of US policy for almost 20 years.

Everything is in place for a change in US-Cuba relations. Cuba has repeatedly stated that it is happy to sit down and have open discussions with the US. In November, even Obama said that old policies "don't make sense." But does he have the courage to break the deadlock when 11 previous US presidents have failed?

If he does, the first question he needs to answer is what he plans to do about the Miami Five.

The fate of these five Cuban men is integral to the future of US-Cuba relations. Their story symbolises the history and discord between the two countries and US aggression against its small neighbour.

Until they are all freed from US jails and back in Cuba, relations between the two countries can never fully heal.

For those unfamiliar with the case, the Miami Five infiltrated terrorist groups based in Florida during the 1990s. These groups were responsible for numerous US-based attacks and bombings against Cuba, most notoriously a string of hotel bombings which injured many and killed an Italian tourist, and the terrible 1976 bombing of a Cubana airline which killed all 73 passengers.

Although all the information they collected about these groups was passed by the Cuban government to US authorities, the five themselves were arrested and charged with espionage in 1998.

Their subsequent trial, conditions of imprisonment, appeals and denial of visitation rights for some family members have been condemned across the world by parliamentarians, Nobel Prize-winners, the UN committee on arbitrary detentions and Amnesty International.

Recent revelations that the US government paid journalists millions of dollars to write prejudicial stories in the lead-up and during the trial have caused the defence team to question the entire integrity of the case and the US legal system during their most recent appeal.

The International Commission of Inquiry into the Case of the Five will investigate all these issues in detail and bring together more than 20 international commissioners, witnesses and legal experts. These were to have included René González, the first of the five to be released, on his first international visit. Sadly the disgraceful conduct of our government has prevented this.

Speaking from Havana before the last-minute denial of a visa, Mr González said: "Our case has been one of the least reported in US legal history despite being one of the biggest and despite involving issues as important as terrorism, espionage and the relations between two neighbouring countries which have been enemies for more than 50 years. I look forward to testifying at the commission in London as I think it will be a fundamental step in breaking the wall of silence around the case and the five."

Victims of terrorism, including the father of the tourist killed in a hotel bombing and the daughter of a victim of the Cubana airline bomb, will appear at the commission alongside other special international guests including Alice Walker, the Pulitzer prize-winning author of The Colour Purple, and legal representatives from the US.

Ricardo Alarcon, former Cuban foreign secretary and president of the National Assembly until last year, will also be coming to Britain and expressed his hopes for the event.

"The fact is that the truth about this case is not widely known and we need to use this event to show what the five were really doing - the non-violent struggle they were engaged in against terrorism.

"We hope the commission will encourage people to feel moved to join with us and put pressure on the US authorities and President Obama to free them and grant them the justice they never received in court."

When the commission publishes it findings it will increase the pressure on President Obama to do the right thing and grant a pardon to these men. Then perhaps real dialogue on the ending the blockade can begin too.

Alice Walker will also be appearing on stage tonight at the Voices for Cuba Concert at London's Barbican Centre which features stars of the Buena Vista Social Club Eliades Ochoa and Omara Portuondo. For full details of this and the commission go to www.voicesforthefive.com or call the Cuba Solidarity Campaign on (020) 7490-5715