Bottle Vase

I feel like I should know this mark but I've been unable to find it, any thoughts?

There is an example of this mark in the unidentified gallery, but I am pretty sure it is Barbara O'Brien's mark (Whanganui). I don't know anything about her, but the work I've seen over the years tells me she was a reasonable studio potter who maybe doesn't deserve to have slipped down the back of posterity's moth eaten sofa.