That is just a lie to prevent you finding out their secrets.

Some friends, after trying to make the famous Scandanavian Iced Berries with White Chocolate Sauce from the recipe in the Ivy Cookbook, and ending up with a congealed mess, concluded that the sole purpose of the recipes is to convince you that everything served at The Ivy (although apparently quite simple) is impossible to make at home so you just have to go to the restaurant. Although I cook quite a lot, I have followed this advice without fail.