A bisexual prison officer is unlikely to ever work again because the harassment and discrimination he suffered at work has permanently damaged his health, an employment tribunal has found.

In two judgments, it was revealed that Ben Plaistow, 41, is likely to receive an exceptionally high compensation payout when his case is finally settled later this year, not only because of the campaign of bullying and harassment his colleagues at HMP Woodhill in Milton Keynes conducted against him during his two years of employment there, but also because of a litany of failings by the Ministry of Justice (MoJ), including the forging of documents submitted to the tribunal.

“Perhaps most seriously, given the identity of the respondent [the MoJ], is the forgery by late production and backdating of documents designed to ‘plug gaps’,” the tribunal ruling states.

It also refers to “corruption of documents by conflation, amendment or post-dated creation” and said the MoJ’s failings go “beyond error”.

The colleagues were found to have engaged in a “campaign of victimisation” against Plaistow, with their conduct found to be “vexatious, disruptive and unreasonable”.

Government lawyers involved in the case were also criticised for failing to demonstrate appropriate diligence and were accused of having “blindly” followed instructions from their MoJ colleagues.

The judge, Michael Ord, sitting with two lay members in an employment tribunal in Cambridge, previously found that Plaistow experienced a campaign of direct discrimination and harassment because of his sexuality, and was victimised and unfairly dismissed because he complained about what took place.

He was subjected to a catalogue of abuse including being called “poof”, “gay” and “vermin”, was pushed and slapped, and had a bottle of water squirted in his face.

Plaistow was hired as a prison officer at HMP Woodhill in 2014 and was fired two years later after he was accused of gross misconduct. In December 2015, he was alleged to have used unnecessary force on a prisoner while breaking up a fight. The incident led to his suspension and subsequent dismissal.

However, the tribunal heard he did not use unnecessary force. This was backed up by CCTV footage and witness testimony from the prisoner, who acknowledged he was at fault.

Expert medical reports found that Plaistow, who was well-regarded by both the prison service and prisoners, was highly unlikely to ever work again. He has been diagnosed with PTSD, moderate psychological damage and paranoia as a result of “lengthy failings” by the prison service. One doctor who assessed him found his condition to be “chronic and permanent”.

The payout he eventually receives will be based on a career-long loss of earnings; Plaistow had hoped to work until the age of 68, so is likely to have lost 27 years of his working life. Final calculations are still being worked out and will include the loss of his £31,660 a year net salary since his dismissal and into the future, as well as the loss of his pension.

As well as awarding him £41,000 for injury to feelings, the top end of the top band in this category, the tribunal has also awarded him £15,000 aggravated damages and £8,000 exemplary damages. These damages are only awarded in rare cases. Aggravated damages are given when the employer’s conduct towards the victim has been humiliating and malicious and exemplary damages are a sign of great disapproval of the employer’s conduct.

The tribunal found that the MoJ’s “conduct as an arm of the state in relation to this case has been unacceptable”.

The tribunal raised further concerns about the training the MoJ promised to provide following the case, which it found to be “wholly unconnected” to the substance of the judgment, relating to discrimination and harassment based on sexual orientation.

“No steps have been taken at management level as to identification and eradication of such conduct amongst staff,” the tribunal heard.

Until the MoJ was approached about the investigation by Plaistow’s lawyers, it had “taken no steps whatsoever to investigate the serious findings and matters of concern”, the tribunal found.

The government department was criticised by the tribunal for not being able to say if anyone had been suspended pending an investigation or whether any steps had been taken to prevent officials from colluding during the investigation.

An MoJ spokesperson said: “We do not tolerate any kind of discrimination in our prisons and take action to make sure all staff are treated appropriately and fairly.

“A new staff network, ‘pride in prison and probation’, was set up in 2016 to support workplace equality and now has 5,000 members. We have noted the judge’s decision and are considering next steps, and a separate internal review is ongoing.”