It's just one of those names...Interestingly enough, Jo is also the heroine of the stories I'm writing/intending-to-write (depending on which one) for the various anthologies!
Springs, it must be contagious.
Oh, and my Jo was for the same reason, so that potential clients may assume it's a man's agency if they wish.
Actually it's my preferred name but everyone around me is used to calling me Joanne. Plus it's useful to have a separate entity for real-life work. For some obscure reason being a sff writer doesn't sell management consultancy. Who knew...