I looked it up (because I know I have read about partridge sexlinked Welsummers somewhere) and according to other sites on the internet, it seems to depend on European/American regional differences. So in the US, you would be right.Duckwing coloring and partridge coloring are different physically and genetically. Duckwing is wild type. Partridge is a double laced type feather. https://www.google.com/search?q=par...=635&safe=active&ssui=on#imgrc=PE8RVqIFmGMWfM: partidge
https://www.google.com/search?q=par...=635&safe=active&ssui=on#imgrc=sscU91rqwlU_jM: duckwing.
The difference is one gene, the E gene.
e+ is duckwing
e^b is partridge.