Ok, so I found that Template: twentyeleven does need to be added to the header.
Please forgive my ignorance as I am completely new to this.
My problem now is that I’ve created a child theme and imported the parent theme in an example to later make only one or two changes. When I select it in my Themes menu for a live preview it looks identical to my site with the parent theme. However, when I activate the child theme I appear to lose a great deal of formating. Why is this?