The convictions of Wayne, 30, and Paul Darvell, 31, for the murder in 1985 of the manageress of a Swansea sex shop were quashed by the court at the end of a two- day hearing and after the Crown said it could not contest the appeal because of the apparent irregularities surrounding police evidence.
After being convicted at Swansea Crown Court in 1986, Paul Darvell was sentenced to 20 years and his brother to 15 years.
Lord Justice Taylor, sitting with Mr Justice Swinton Thomas and Mr Justice Judge, told the court that the appeal would be allowed and the men freed; the reasons will be given later.
Outside the court, the men were reunited with their two other brothers, Robert and Derek. Wayne Darvell said he held no grudges against anyone: 'We have been waiting for this moment for a long long time. I am very pleased it has come at last. I would like to thank everyone who has stood by us - family, friends and lawyers.'
Paul Darvell, who went bald during his time in prison, added: 'It's great to be free. We can't wait to get home. I lost my hair through all the stress. I just want to go and have a pint of shandy. It's been a long time.'
In a statement issued last night, Robert Lawrence, the Chief Constable of South Wales, said he 'deeply regretted' the wrongful convictions. The murder inquiry would be re-opened.
The appeal was based largely on evidence gathered by Devon and Cornwall police, who were asked to investigate the convictions following submissions to the Home Office by Justice, the law reform body and the BBC's Rough Justice programme.
Discoveries of irregularities in police evidence led to the widening of the inquiry to examine other records at Swansea police station.
In February, seven detectives were suspended, of whom four were alleged to have been involved in other cases in which a total of 12 other people were convicted.
A total of 87 officers have been named in more than 50 complaints files being completed by Devon and Cornwall, whose officers seized nearly 1,500 pocket books for scientific examination. The Crown Prosecution Service will be asked to decide whether officers in a number of the cases, including the Darvells, should face charges. A number of other officers have also faced discipline proceedings.
Using ESDA testing, Devon and Cornwall police discovered that detectives' notes of their interrogation of Wayne Darvell, which they said in evidence had been contemporaneous, had not been compiled until long afterwards and the originals were destroyed.
They had been based on a 150- page statement by a detective - which he had said on oath was made after the interviews. Counsel for the Darvells said the 'doctored' statement was a blueprint for the interview notes.
Another detective who took part in the interview and claimed the notes were written up immediately afterwards was found to have made them in a pocket book that was not issued until two months later.
Scientific evidence, including the fact that examination of a palm print in blood excluded the two men, was kept from defence lawyers. Det Chief Supt Don Carsley, then head of South Wales CID, also ordered fingerprint experts to stop further work on the print; photographs and negatives were destroyed.
Detectives also ignored warnings from two local uniformed officers that Wayne Darvell, who implicated his brother in the confession, was a habitual confessor who hung around police stations, saluting officers and volunteering useless information. A psychologist who later examined Wayne Darvell said he was 'suggestible and gullible' and would name others if it earned him the favour of those in authority.
Police secretly taped conversations between the two brothers in the cell during interrogations, but did not tell their lawyers. Counsel on both sides agreed yesterday that the tapes contained statements which the men would have been unlikely to have made if guilty and would have supported their case.
Statements by two detectives that they saw the Darvells near the scene of the murder on the day were wrong because examination of their diaries proved them to have been elsewhere at the time.
Detectives were also alleged to have planted an earring - similar to one possibly worn by the victim - which was found in a police car after it had taken Wayne Darvell to the police station.