Avon and Somerset police have apologised to a young woman who was handcuffed in her bedroom by a group of male police officers while partially undressed. Katie McGoran, who had attended a “kill the bill” demonstration in Bristol in March, claims she was left “traumatised and humiliated” when police officers pretending to be postal workers tricked their way into her shared student house and burst into her bedroom. The Observer reported at the time that the 21-year-old photography student, who has no police record, was put in handcuffs for more than 20 minutes by the four male officers, while wearing a short dressing gown. She says she was not released even though she became increasingly distressed and suffered repeated panic attacks. At one point, she claims, the officers, who were not in uniform, watched as she was brought to tears struggling to pull some joggers on while still restrained. An investigation by Avon and Somerset police – prompted by a complaint by McGoran and seen by the Observer – concludes it was unacceptable for officers to keep her in cuffs after it became likely she was not the person they were seeking and any perceived threat had diminished. Bodycam footage examined for the investigation shows she was “obviously shocked and distressed” at the presence of the male officers in her bedroom. There were questions whether in the circumstances it was “proportionate to immediately handcuff her when another option could have been to wait until she was dressed”. The footage also appears to show the officers failed to introduce themselves or explain why they had entered her home. The investigation report says it was unacceptable for the officers not to read McGoran her rights and for some of them to be without face masks given the “obvious public health considerations”. The force should have considered sending fewer officers inside and deploying a female officer as “the suspect was a … female student with no previous police history”. None of the officers, however, will be facing disciplinary action. The report also defends what it calls “the postman tactic”, which it says has been used for decades. It claims its use was acceptable and lawful. Avon and Somerset police’s high-profile investigation into clashes over the police, crime, sentencing and courts bill, which left 46 officers and 62 protesters injured, is still under way, with further arrests last week. So far 71 people have been held in one of the force’s biggest operations. Inspector Alex Matthews, from the force’s professional standards department, states in a letter to McGoran that the officers acted entirely out of a sense of duty: “They have intended to act professionally throughout and have done so. However, where we fall short on some occasions, we must accept that as a force and as individuals and develop ourselves to prevent any mistakes and improve.” The letter adds: “I would like to apologise for the areas where it is felt that the service was not acceptable.” The apology comes after an inquiry by the all-party parliamentary group on democracy and the constitution found Avon and Somerset police gave the impression of “revenge policing” because of the excessive measures employed to investigate alleged offences committed during the protests in Bristol. It said the tactics used against McGoran and 16-year-old student Grace Hart, who was raided by officers armed with Tasers pretending to be making a delivery, appeared “calculated to coerce and intimidate”. McGoran said was she pleased the police had finally acknowledged what happened to her but it shouldn’t have taken a complaint to get an apology. “I was treated without respect and without dignity,” she said. “They should have known at the time it was wrong. They could see the emotional damage they had done to me.” She said she had attended the demonstration because she was concerned about threats to the right to protest and the criminalisation of persecuted minorities, such as Travellers, under the government’s controversial police and crime bill. She said the police appeared to want revenge when they arrested her in her bedroom. “They had no reason to think I would be violent, so why did they handcuff me? It was like a punishment because I had been on the protest. It was revenge policing.” McGoran said the raid had left her fearful. She gets flashbacks when she encounters police officers or hears sirens. “It was very traumatic,” she said. “I’d like to seek out therapy but they haven’t given me any compensation.” She said the incident had destroyed her trust in the police. “If there’s ever a time I need the police, I’m not going to be able to feel like I can call them.” While the investigation report says Avon and Somerset police did not meet all expected standards, it rejects McGoran’s claim the officers used unnecessary and excessive force to enter her bedroom. Avon and Somerset police said legitimate policing tactics had been used against McGoran but that bringing a female officer would have been beneficial. It said officers were acting out of a sense of duty and were seeking to apprehend those involved in “disgraceful scenes of violence” during the clashes. “While no individual conduct issues were identified, we fully accept there were aspects of our interaction with Ms McGoran which fell short of the standards we know the public expects,” said a spokesperson. The force said a separate investigation had found the service provided to the 16 year-old-girl, Hart, who was also raided, was acceptable. The force rejected any suggestion it did not facilitate peaceful demonstrations. “In Avon and Somerset, we have a proud history of facilitating protests and recognise it’s a democratic right enshrined in law,” said a spokesperson The chair of the all-party democracy and the constitution committee, Geraint Davies, said the police had abused their power during the arrest of McGoran. “The raid was brutal and humiliating,” he said. “A grudging apology is not enough, if they think bursting into a young woman’s home, who is barely dressed, on false pretences, is an acceptable tactic. It was completely disproportionate.” Davies called on ministers to put in place a charter to protect the right to protest as police forces such as Avon and Somerset could not be trusted: “The right to peaceful protest is fundamental to promoting democratic change, whether it is the suffragettes, trade unions or climate campaigners.”