Two families who were victims of one of the UK's biggest miscarriages of justice are hoping Tony Blair will make an apology.
Gerry Conlon has campaigned for a public apology
The prime minister is expected to comment on the wrongful jailing of 11 people for IRA bomb attacks on pubs in Guildford and Woolwich in 1974.
Members of the Conlon and Maguire families had hoped the apology would come during Prime Minister's Questions.
The move follows a substantial campaign in Ireland for a public apology.
Eleven people were wrongly convicted of making and planting the IRA bombs which killed seven people.
Most of those convicted were either members or friends of the two families.
The prime minister's spokesman said on Wednesday: "All those involved in Northern Ireland live with the pain of the past and the unfortunate fact is that you can do nothing to change the past.
"Sometimes there's a possibility to ease the pain of the present and the decent thing to do is to take that opportunity."
The spokesman denied the timing of the apology had anything to do with the current political situation in Northern Ireland.
All seven people were arrested because of a family connection to Gerry Conlon, one of the Guildford Four who was wrongly convicted of planting the bombs.
Mr Conlon's father Giuseppe was arrested when travelling to London from Belfast to help his son. He died while serving his sentence.
Mr Conlon said he felt his name had not been cleared and there had been a "whispering campaign" implying they had been let out on a technicality.
Speaking as he went into the House of Commons, Mr Conlon said a public apology was an important step in helping the families recover from their ordeal.
"What's happened to me is just unbelievable but I'm not the only one," he said.
"If you can damage people in this way and you have the ability to try and repair their lives in some shape, you have to do it."
Earlier, he told BBC News: "I'm hoping for some sort of closure on this."
Also arrested were family members of Anne Maguire, the relative with whom Giuseppe planned to stay in London, as well as two family friends.
They were all jailed for handling explosives, based on scientific evidence which was later entirely discredited.
In October 1989 the Court of Appeal quashed the sentences of the Guildford Four, and in June 1991 it overturned the sentences on the Maguire Seven.
Mrs Maguire said an apology would be very welcome.
"It will mean that our family, my children, their children and our great grandchildren too will be able to live in their country without a slur on the name and it will give me peace of mind if and when I join my husband who has died," she said.
"It will be a great day but it will be a sad day too because Giuseppe and Paddy are not here with us."
The Conlon family has received a private acknowledgement that there was a miscarriage of justice but has campaigned for it to go further.
Mr Conlon's case was highlighted in the Oscar-nominated film In The Name Of The Father, starring Daniel Day-Lewis.