This happens so often at the school gate, chatting to Mum A (1-2-1) and along comes a Mum B (who is an acquaintance of both A and myself) and immediately Mum B starts speaking to Mum A as if I am not even visible. No acknowledgement, no hello, just assumes her presence is more important than my own. Several of the mums seem to do this as a matter of course and it seems very rude...?