Thanks for the replies. The independent expert is a well respected person in my field who offers a professional, not-for-profit advice in this sort of cases.

I have got into a dispute with my former employer and we're trying to resolve it through negotiations. I would like an independent expert, who's familiar with that sort of dispute resolution, to represent me. At the same time, I would also like my trade union to provide their inputs during negotiations, possibly representing me at times. Is this doable? Can more than one person represent you?

Why would I be getting involved in this several years after leaving... Well, I cannot give details, but essentially my ex-line manager has been doing something seriously wrong (it relates to public interest) and the only way he could 'justify' his wrongdoing was by ridiculing my work over there. I found out about it recently and hence I had to state the facts to the top people. And I do have the proof of whatever I have said to the top bosses. But it seems they are all the same. Thanks for the helpful replies.

I used to work in a firm a few years ago and when I left that work, my record was very clean there. Hence, there would have been no reason for the HR to give a negative reference about me to any future employers. I was on good terms with everyone. However, recently I came to know of some serious wrongdoing my line manager was getting involved in. I can't give the details, but it related to public interest, so it was very important to alert the 'higher up' bosses about this in that firm. So I wrote to the people at the top about it. But when I alerted the top people, they actually defended the 'wrong-doing' line manager and, to my shock, started threatening me about the 'consequences' if I did not stop raising this matter. I can't believe they are doing that. Now my worry is, can they change my reference in the 'official' records after an employee left work on clean record? I am asking because I heard, many employers ask ex-employers a question like, "would you re-employ this person if he/she applies again?" Earlier my ex-employer may have said 'yes' to that, but can they change this answer in the 'official' file?