HUGE meat platter (I think)

Hi, newbie here,and I’m so glad to find you all! I went to an auction earlier today and purchased a box lot of sterling and silver plate. Was planning on keeping the one item I really wanted and selling the rest. But I’m stymied about the value of this platter.

To begin with, it’s enormous. 23" long and 18" across. It’s also heavy, weighing upwards of 10 pounds. Think how heavy it would be with a big roast on it. It also looks like there is a compartment under the platter for a water bath. (Water? More weight!)

It has the eight cross arrows hallmark which I think means either Wm Hutton & Sons or T & J Creswick, depending on when it was made. It also has an embossed B, which is probably a year. There are no other markings on the underside that I could find.

On the top, there is an etched figure of a winged horse coming out of what looks like water.

Can anyone tell me anything about this, its age, whether it is Creswick or Hutton, or someone else? Also any guess at value would be appreciated.

Thanks so much.
platter4 winged horse.jpg
platter3 hallmark.jpg
platter1 front.jpg