I don't recognise the piece, but like Frank, I did think that 589 could be May 89, or it could be S 89 for Summer 89 or Studio 89 depending on how it was set out. From the photo of the signature it could possibly be Fladgate, which would suggest Deborah Fladgate, but I reiterate that I do not recognise this as a piece of her work (which doesn't mean that it isn't hers).
You would need to look at the signature again to see if Fladgate is a possibility and then if so seek confirmation directly from her.
Signatures are difficult to photograph.
