HR bod here. The main thing is, is there evidence of the bullying? Actual independent evidence such as emails, witness statements etc. Without this the grievance will fall flat. Most of the time any independent witnesses are too scared to publicly support the grievance-raiser, despite what they may say in private. Or they will end up a target too. And most bullies are too clever to ever say anything in email that can come back to haunt them.
I have two friends who raised grievances against a manager who mercilessly bullied anyone who had the misfortune to be his direct report. Both upheld. One got a new job out of it because the bully had written an untrue performance report that had prevented him from applying from promotions. The other got financially compensated with a backdated performance related pay increase he has missed out on because of the bully. Both still have flourishing careers within the same organisation.
It was career suicide for me but we didn't have a proper HR department. I got moved to another job while this bully stayed there. I felt I was moved because as their words she was needed in the department more than I was. That was my cue to look for another job and I left.
Thanks all, that’s what I feared really. Pixiedust did you have to Declare anything about the grievance when you applied for other jobs? My friend is already looking for another job which feels so unfair.