Tessagin the batter mix is easy to make getting them to rise and cook properly is the difficult bit. The key is to heat the oil until it is very hot and the batter sizzles as you pour it in the tin.
I had Yorkshire Pudding in England in the 60's. I love it!! It was originally made to eat with the gravy, before you had the meat entrée, so as not to eat very much meat. It was a cheap filler-upper.
I'm a Devon girl, and my Nan used to make the best Yorkshire Puddings....cooked in the roasting pan with hot beef drippings.....Nan's long gone, but I think of her often.