I have a "chamber pot ", in mint condition. The mark on the bottom is the " Doulton " mark of 1891 to 1902. But there are other marks that I don't understand. These are........

A small cross.....A cresent moon.....D997 with an ( m ) under it. These marks are all in blue, but there is ( 80 )marked in red under the ( m ).

Here is an example of the marks.
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+ ( D997
m.
80

Also the larger " Doulton Mark " is there.
DOULTON BURSLEM ENGLAND TUDOR

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The pot is....A white background......A large tree in blue and red....With gold trim. Any information would be gratefully appreciated.