Hey PEPA44,
Where was this blade from? The reason I ask is that the DHA stamp may be specific to De Havilland Aircraft of Australia. The A in the DHA would be to differentiate the usual DH over xx in a circle or sharp-cornered triangle of De Havilland Aircraft of England from the De Havilland Aircraft of Australia. I noticed what look like a couple of inspection stamps shaped like upside-down triangles with rounded corners on the flange of the propeller, and I think these are indicative of De Havilland in Australia. According to Wikipedia, De Havilland of Australia began manufacturing propellers in late-1930s, for use domestically and by De Havilland of England.
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de Havilland Australia - Wikipedia"
Also, if you could measure the overall length it might help eliminate some aircraft types as it would be too large or small.