Pictured below is a Bulldog planter in the Matt Blue glaze.  Gifford's book categorizes it as "Niloak Castware", and "Hywood by Niloak".  He also sets a value estimate of $50-75 as of 2001.  I don't expect that to hold at auction.  You can see an example of the tan variant on Plate 140, Page 233 of his encyclopedia.

The figurine is two inches tall and five and three fourths inches long.  This planter uses one of the Lewis glazes.  The Niloak label is embossed on the bottom. 

Below are a couple of current Niloak auctions.  Buldogs are not that common so I couldn't restrict the search to only them.