Well I see 3 possibilities:
1.Since the forum talks about her area of interest, like children's welfare and mental health, it was most likely why she was there and like Countessmeout said, Big change has an interest in them as well. She could have gone before and maybe she wasn't recognized
2. It occurred to me, I remember Bea having lunch with the British Consul General, New York and Director General for UK Trade & Investment sometime in 2016. Maybe, somebody for there invited her to go or told her about it.
3. It could have the DOY connections most likely unofficial though.
I'm leaning towards 1 and maybe 2
I have too much time to hypothesize on this