To date post 1927 Royal Doulton pieces look at the base of the item and usually you will see a number to the right of the standard back stamp. By adding this number to the year 1927 you will have the date of your piece. For example if the number is 12 then the piece dates from 1939 etc.

Unfortunately not all pieces have a number but at least with the ones that have, you can be assured of the date. An example of a piece from 1943 is pictured below.

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