I had reserved this time to answer my e-mail but as I am really tired I decided to surf the web instead for information about medieval smocked aprons and how to make them.
Here is what I found:
Aprons in Medieval Art
Pleatwork embroidery, a very useful website! But alas a lot of it is under construction...
A version made by
Matilda la Zouche, one of my favorite costumemakers.