Long story short, I was bullied out of my last job and luckily got away to the much better job I have now. A senior colleague at the other job really supported me, but ended up in the firing line for that and other reasons. I've now been asked to attend a grievance meeting for ex colleague as a witness, which I am going to do. Just wondering if anyone has any experience, could it have any impact on my current job / future job prospects? And am I obligated to tell my current employer that I'm going?