Antique English Frog Vase

I received this vase from my grandmother with no information. It has been stored in my hope chest for over 20 years. In the little research I have been able to do, I think it is called a Frog Vase. The bottom of the vase says, " Made in No. 6 ART ENGLAND. Any information would be appreciated. I have always thought it was unique and beautiful hence the reason I have kept it all these years. I would love to know the history so I can continue searching it out and get an approximate value on the piece.