Hi Nico,
From what I've learned thru the intermediary, my aunt (sounds strange saying that) always had a gut feeling that her eldest sister (my b/mum) had had a child but was not sure until a few years ago. My b/mum never married but had a life long companion. When the companion died a few years ago she told my aunt that my b/mum had confided in her, but never another soul. The companion only told my aunt just before she died because she thought someone else ought to know, just in case just such a situation as this arose.
The intermediary was very careful in wording the initial letter and just mentioned that she was acting on behalf of a client and needed to know if her oldest sister was born on such and such a date. My aunt apparently replied straight away by phone, confirming the date of birth and enquiring if the 'client' was a child adopted many years ago.
Anyway, to the point, my aunt has seen my photos, I have seen a photo of her. She did want to meet up, but after talking to her older sister, she agreed to her wishes not have further contact.
It would be nice to meet even just once to say hello, tell my birth mum that I hold no grudges, and just find out a little of my identity and pre-adoption history, short as it is.