Although your experience pilot friend said he was going to report him, he may in fact have meant as an airprox.
The airprox system is in place so if you feel you have had a close call, you can report it, it's not a system of blame, it's an assessment of whether a near miss actually occurred, and what could be done in either training or legislation to avoid similar events.
I've had two such reports filed, one where we were both flying over a local gathering, I feel we both learned a valuable lesson about extra vigilant when looking at something other pilots may well be wanting to look at, and one with a fast jet low level, which probably happens every day.
You could file a report on this occurrence if you felt that a near miss took place, but it is ideal if both parties file a report.
UK Airprox Board