I am guessing (don't roll your eyes!) that it is 15 inches.
To my surprise, I found that early issues of Australian Smocking and Embroidery had quite a few doll patterns. I suspect this is because there were a few women around then (early 1990s) who were collecting china dolls and making clothes for them, rather than people dressing dolls for children.
I made it sleeves - giving it a better chance of fitting the doll.
I also made the matching bloomers.
I find machining such small items quite hard, although I don't mind the handwork. It's been a good use of fabric and Brigid was pleased with the result.
