I was the other pilot in this near miss. Just to give more context it was a pre-start in a competition day, there were a significant number of sailplanes in this thermal, a number of which were at or about my altitude, not to far under cloud-base in rather murky shady visibility.
In this situation where Anton was approaching a thermal with many sailplanes Flarm is of limited use. Yes it will warn of predicted collision danger which should be heeded, but that is an adjunct to "Mark 1 eyeball". Anton and I saw each-other at the same time and he did everything right from that point and the situation was sorted.
I think it is one of those situations which will statistically arise from time to time and it is training and airmanship which will save the day, not the reliance on Flarm.