An SAS sniper jailed for illegally possessing a gun has become "gaunt" and is "struggling with being locked up for 16 hours a day", his wife says.
Sally Nightingale met her husband Sergeant Danny Nightingale for the first time since he was sentenced almost two weeks ago.
The serviceman, who served in Iraq and Afghanistan, was sentenced to 18 months in military detention by a court martial after pleading guilty to possession of a prohibited firearm and ammunition.
After the visit at the Military Corrective Training Centre in Colchester, Mrs Nightingale said: "I saw my husband Danny at the military prison today. He was trained to deal with being detained by the enemy - it is impossible for him to understand how he has found himself detained at the hands of the country he has served so loyally for over 17 years."
Mrs Nightingale, accompanied by Sergeant Nightingale's father Humphrey, said her husband is finding his situation difficult, but is "humbled" by the public's support.
She said: "Danny is gaunt and as someone who has enjoyed an active and outdoor life, is struggling with being locked up for 16 hours a day. However he is being treated professionally and with compassion by staff and making a contribution to the training of other detainees.
"My husband is overwhelmed by the public support. He has received letters from members of the public and when told of the level of support he has is genuinely humbled."
The case has sparked controversy, with supporters claiming the father-of-two, who has served for 17 years, including 11 with the SAS, has been betrayed.
Mrs Nightingale has written to the Prime Minister asking to meet to discuss the "injustice" of her husband's sentence.
Sgt Nightingale pleaded guilty to illegally possessing a 9mm Glock pistol which had been packed up and returned to him by colleagues after he had to leave Iraq in a hurry to help organise the funeral of two friends killed in action. He also admitted possessing ammunition.