DH works in a niche industry. There are three companies working in this industry in the UK (none of them are British owned) and employees tend to flow between the three of them.
3 years he was sacked from a senior position by one of them (company1). It was an outrageous situation. There was a (very big) mistake by one of the team, DH was in charge, someone in the US said "heads must roll" and it was DH who went. The mistake occurred because people were over worked, under supported and correct procedures had never been used because of the cost. DH filed a case for unfair dismissal and they settled out of court - a very substantial compensation payment, thank you very much.
He's now working for one of the other companies. He was taken on by someone he'd know at the first company who was then working for the new one. That person didn't know why he'd left company 1 though. DH said something about ridiculous working conditions and it being time to go, which his new boss accepted, as he knew exactly what it was like.
Since then, 4 more employees from company1 have joined the team where he is now. They have all said to him privately that they were outraged by the way he was treated at company1 and that was a big factor in their decision to leave. Not solidarity with him, that would be a bit much to ask, but the shoddy way they treat people. Those who were senior enough to know all the details have told him that company1 was relieved in the end not to have to pay him a lot more.
Every time I hear that another person from company1 is starting it worries me that they'll spill the beans, or that one of the existing "nice" ones will get upset with DH over something (like you do with your boss sometimes) and tell all. What would DH's position be if it did come out now, after 3 years?