William Cook Antiques has dated this piece to the 19th Century.
In 1876 The Centennial Exhibition was held in Philadelphia to celebrate 100 years of Independence from England (it was similar to our own Great Exhibition in Crystal Palace). At the Exhibition the Horstmann brothers exhibited various flags of this exact size including those of a number of European countries. This flag I believe was shown there and is stencilled with Horstmann brothers name and the country name Belgium.

This flag has been framed behind UV plexi glass and stitched onto a backing that has been treated so that it does not react with the antique fabric of the flag. To my knowledge, this is the only Belgium example still in existence from the exhibition.
William Cook Antiques has dated this piece to the 19th Century.
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