Maxalt,
Your mate and Company probably didn't get any feedback because it's pointless for ATC to spend the time doing so, even when they review it. Perhaps the review found that your mate wasn't at an assigned speed. Maybe your mate expects an apology because maybe he thinks he's operationally perfect. But maybe your mate helped create the conflict in the first place. Maybe, your story is nonsense.
Next time London ATC drops the ball with me, I'll be sure to demand a full-blown investigation and follow-up written report, delivered by hand via courier service to my doorstep. If I don't receive it, it can only mean there's an ongoing cover-up. After all, what happens to me is just that important, and I'm sure they have nothing better to do.