A man has admitted pelting Sir Stuart Bell with eggs at a Remembrance Sunday parade, the latest incident in a 20-year dispute.
Terry Dixon, 54, from Liverton Avenue, Middlesbrough, attacked the town's Labour MP on November 13 last year.
Dixon changed his plea to guilty at Teesside Magistrates' Court, after previously denying assault.
The court heard today that Dixon is unhappy with the way police investigated an assault on his son that left him with "horrific injuries", and that when he contacted Sir Stuart for assistance, it was not given.
Dixon's lawyer John Nixon said: "Many years ago my client's son sustained horrific injuries in an assault. My client found his son unconscious in an alley.
"A man was convicted of an assault against him. But he doesn't think this investigation was carried out thoroughly or properly.
"The history is that my client contacted Stuart Bell seeking assistance and full assistance was not given.
"My client's actions were borne out of a long sense of injustice."
Dixon, speaking outside court, said: "What do I have to do to get justice for my son? I'm still jumping up in my sleep, picking my son up off the floor who's not there.
"I suffer post-traumatic stress, as soon as I go to bed and it gets dark, that's when the nightmares begin, it's never left me for 20 years. Twenty years of mental torture, 20 years of jumping up in my sleep, 20 years of smelling that grime and oil in the alleyway and 20 years of begging Stuart Bell to help me that's fell on deaf ears.
"I've hit him on the head to draw attention, I know it's wrong, I shouldn't have done it but what do I have to do to get justice?
"I am guilty, I did do it."
Sir Stuart was criticised in the Independent newspaper last year after it reported he had not held surgeries for 14 years.
Today, Sir Stuart refused to comment on the case, saying he had already made a statement to the court that he no longer holds open surgeries as Dixon has been attacking him for 20 years.
Dixon will be sentenced on March 5.