Definitely not like any John Walsh I have seen. All of the pieces have been small and the signature is pretty distinctive once you know it. (see Below for 4 examples)
I think it starts M


? but it is not similar to any of the signatures I have for MacKenzie Mitchell, Mark Eliott, Mark Galton, Mark Kalifa, Mark Thiele, Martini Glass, Mat Quicke, Matt Bryce, Matt Larwood, Matt Ryan, Matthew Farrell, Maureen Williams, Mel Fraser, Michael Hook, Michele Super, Mike Shaw, Misty Anne, Mitch 04, Moshe Pleshet, Madeleine Prowd, Mariella Mckinley, Matthew Goodlet, Meg Caslake OR Morton Yeates. It is a new signature to me. Good luck.
Ross