The Belfast-born human rights campaigner said the identity of the real bombers was common knowledge at the highest levels of both the IRA and the British government, and he asked the people of Birmingham to back the campaign.
“When I heard about the small number of people who had signed this petition so far, I was gutted,” said Mr Hill, who served 16 years of a life sentence before the conviction was quashed.
“I knew I had to sign it. I am very surprised and disappointed that the people of Birmingham are not taking this more seriously. They must have short memories.
“I just cannot believe that they have not risen up about the murder of 21 innocent people in their own city.”
Mr Hill signed a petition organised by a sister of the one of the victims demanding the case be reopened and forensic tests taken.
Two pubs, the Mulberry Bush and the Tavern In The Town, were targeted on Nov 21, 1974. Mr Hill, Hugh Callaghan, Gerard Hunter, William Power, Richard McIlkenny, and John Walker were convicted of murder and conspiracy to cause explosions in 1975. They were freed in 1991 but police have failed to charge anyone else.
“In the years since our release we have learned the truth,” said Mr Hill. “We have been told the names of the real bombers. We know who they are, we know where they are. So does the British government. So why have they never done anything about it?”
He said he was disgusted by the lack of action from West Midlands Police, one of Britain’s largest police forces.
“The case files on the actions of the police and the judiciary in this case have been sealed for 75 years. Can you believe that? They must really want this one to go away. That is the only thing I can conclude.
“It is nothing short of outrageous, and the worst thing for everyone caught up in this. If the police had just done their job properly in the first place they probably would have caught the real bombers themselves.
“The people of Birmingham need to take a long hard look at themselves. Are they prepared to let the slaughter of 21 innocent people go unaccounted for, or are they going to sign this petition and demand that the case be re-investigated?”