David at the Bourke Steet Bakery gave this response when I asked them what they used:
"The flour that we use has 13% protein content which makes it a fairly strong flour. The recipes in the book are most suited to flour of this type so we would recommend that you use a strong or bakers flour, check the protein percentage on the label."
Now we just have to try and make them look and taste like his! Some great pics and story from David Lebovitz on his trip to BSB last week - he was impressed, which is something, given that he lives in Paris.