Her actions are part of a new campaign by a coalition of church leaders and ordinary members of the public to free the remaining 50 or so Zimbabwean immigrants still held indefinitely in detention centres around the UK.

Most of the detainees are former criminals who remain trapped in immigration detention centres because the Home Offices refuses to release them even though they have served their time in jail.

In normal circumstances the government deports refugees convicted of a criminal offence back to their home country but, because of the current moratorium on deporting Zimbabweans, many remain trapped in detention centres.

Supporters say the majority of those still incarcerated were convicted of non-violent offences such as using false passports or documents and that their continued incarceration constitutes indefinite detention.

Mrs Percy and her friends won their first victory recently after the Asylum and Immigration Tribunal granted bail to three Zimbabweans who were being held at Haslar. Some of them had served nearly a year beyond their original custodial sentences. 

They now hope their successful tactics will encourage other people to come forward willing to act as guarantors for other Zimbabwean detainees. The guarantors risk losing substantial amounts of cash if the detainees abscond or fail to abide by their strict bail conditions.

For Mrs Percy, however, that risk was one worth taking. She put up £300 for "Jorem", a Zimbabwean  who had served two months in prison for using false documentation. At the end of his custodial sentence he was taken to Haslar where he was being held indefinitely. 

"It's disgusting that so many Zimbabweans are kept in custody even after they've finished serving their sentences," said Mrs Percy. "Most of the Zimbabweans I have met were put in prison for crimes like using false passports. Now that may be wrong, but it's very different from a hard crime. Besides, people should be free once they've paid their debt to society."

Michael Wooley, co-ordinator of the Haslar Visitors Group, which provides support to asylum seekers and immigrants in detention centres, said he had initially tried to find celebrities who would be willing to act as sureties for the Zimbabweans but no-one came forward.

“It meant we had to rely on ordinary people to put up the cash and time," he said. "It's a big commitment guaranteeing bail, you have to spend a lot of time with the person once they've been released, not to mention the possible loss of money. But remarkably lots of ordinary people have said they were willing to do so."

Mr Wooley himself put money towards a £1,400 bond for George Muchapirei (pictured), a 29-year-old Zimbabwean asylum seeker who served a two and a half year sentence for forging cheques and has spent nine extra months in detention despite his custodial sentence coming to an end last November.

One of the most high profile figures in the campaign is Dr Nicholas Sagovsky, Canon Theologian of Westminster Abbey and a member of the Independent Asylum Commission. He appeared at the tribunal to act as surety for a 20-year-old Zimbabwean national who had languished in a detention centre despite being freed from prison nine months ago.

"These people may have been in prison but they have served their time," he said. "The only reason they are still kept in detention centres is because the government cannot deport them to Zimbabwe. But how long is the government willing to keep these people? It could be years before Zimbabwe is safe for these people to return to.”

As George Muchapirei was freed from court his supporters rushed to embrace him and then burst into tears.

"I never thought this day would come'' he said "I can't believe I'm free, I think it will take a few days for it to sink in.'' He added: "Forging cheques was a stupid thing to do. It was at an immature time in my life and I would never do it again''.

He will now have to report to the authorities three times a week but Michael Wooley said he had no doubts Mr Muchapirei would stick to his bail conditions: "I think the fact that members of the public are putting up bail money will encourage these Zimbabweans to make sure they stick to their bail arrangements. I don't think George will let me down.''

If you'd like more information about acting as surity for asylum seekers Haslar Visitors Group and Bail for Immigration Detainees are a good place to start.