A prison officer left covered in blood after an angry lag headbutted him had a 'premonition' that he was going to be attacked, a court heard.
Geoffrey Hampshire, 46, assaulted the officer at Forest Bank prison in Salford after having a 'difficult day'.
The officer was left with a broken nose and suffered 'copious blood loss'.
The attack led him to undergo a 'dramatic loss of confidence'.
Manchester Crown Court heard the officer had already planned to leave Forest Bank after working there for four years.
"He had a premonition, having for so many years not being assaulted that things were going to go wrong for him," prosecutor Andrew Evans said.
Before he left his job his fears were proved correct when Hampshire, who was serving a jail term for burglaries and conveying drugs into prison, headbutted him in a 'spontaneous' attack.
On July 27, 2018, Hampshire was due to be taken to court from prison to be sentenced for burglaries, for which he later received a 45 month jail term for.
But he became frustrated after he wasn't taken to court for the hearing.
Read more of today's top stories
There was also an incident when Hampshire was refusing to return after exercise.
Later he was being taken to the medical area to take his medication when he became angry with the officer while they had a conversation.
Hampshire said the officer was 'taking the p***' and that 'this place [prison] is a joke'.
Then in an 'entirely unexpected' development, Hampshire headbutted the officer between the eyes, landing on the bridge of his nose.
The officer was covered in blood, suffering a broken nose and bruising to his eye.
In a statement later, he said: "I felt embarrassed. I couldn't believe I had let this happen to me.
"I became very emotional because I doubted whether I could do my job correctly."
David Farley, defending, said Hampshire wanted to apologise to the officer and that he regrets his actions.
He said Hampshire, who has since been transferred to HMP Birmingham, had a 'difficult day' and had not been taken to court 'against his wishes'.
Hampshire, who was already serving a total of five years in prison, had misunderstood the intentions of the officer and made a 'poor response', Mr Farley said.
Sentencing Hampshire to an additional six months in jail after he pleaded guilty to unlawful wounding, Judge Alan Conrad QC told him: "You headbutted a prison officer who had done nothing to warrant what you did.
"He was a public servant doing his job in difficult circumstances."
