The case of an SAS sniper jailed for illegal possession of a weapon has sparked a political split after Attorney General Dominic Grieve turned down Philip Hammond's request to review the prosecution.
Sergeant Danny Nightingale's wife was left "disappointed" after Mr Grieve said it would be inappropriate for him to review the decision to prosecute.
Sally Nightingale had earlier said the Defence Secretary's request had given her "real hope" that her husband may be home for Christmas.
But after Mr Grieve's announcement, she said: "I was extremely hopeful of an early decision on Danny's fate after the announcement of the Defence Secretary, who asked for a review of his case, so I am very disappointed that the Attorney General has refused to do so.
"The appeal is being lodged tomorrow and I hope that he will at least consider reviewing any decision by the Service Prosecuting Authority to oppose the appeal and seek a retrial if Danny's conviction is quashed."
Sgt Nightingale's lawyers are expected to lodge an appeal against his conviction and sentence on Wednesday, as well as apply for bail. They said they remained confident at the prospect of an appeal.
The father of two, who served in Iraq and Afghanistan, was handed an 18-month sentence in military detention after admitting possessing a prohibited firearm and ammunition.
The case sparked widespread outrage from SAS veterans as well as MPs who were due to debate the case.
Defence Secretary Philip Hammond wrote to Mr Grieve, asking him to review whether proper consideration was given to the question of Sgt Nightingale's prosecution was in the public interest before the case was brought to court martial.
But a spokesman for the Attorney General's office said: "It would be inappropriate for the Attorney General to review either the decision to prosecute or comment on the appropriateness of the sentence. That is a matter for the Court Martial Appeal Court in due course."