This is an antique dinner plate in the Blue Willow Pattern from sometime in the 1800s - Georgian / Victorian.
It has a ribbon shaped backstamp with Warranted Staffordshire as was in use by a number of potters on their Willow pattern ware.
Under it there are the initials JM & S - my Goddens states that there were 3 staffordshire potters using these initials -
Job Meigh & Son Hanley c. 1812-34 / John Meir & Son Tunstall c, 1841-97 / John Maddock & Son Burslem c. 1855-69
I haven't been able to narrow it down, although sometimes you can if they used different borders to mark their willow wares.
This is a heavy plate. There are 3 sets of stilt marks on the underside each in the triangle shape, these stilt marks are also partially visible on the topside of the plate, which I am pointing to in the photo.

I have a large quantity of Blue Willow currently waiting to be listed, please see the last photo. So please check back and see what's new. 

Condition is very good, there are no chips or cracks, just some fine crazing. Please see photos.

Diameter 26cm / 10¼ inches
Weighs 690g

Rest assure I carefully pack all my items to ensure that they arrive with you safely.
I send my item via Royal Mail and am happy to combine postage, but this is not possilbe for overseas orders.
International purchases need to have the items combined prior to purchase to benefit from postage savings.

Thanks for looking, happy shopping, Maggie