Interesting post and I agree – there are not many successful popular science books I think that have a lot of mathematics. Penrose’s Book “The Road to Reality: A Complete Guide to the Laws of the Universe” is not as famous and well sold/appreciated that Stephen Hawking’s “A Brief History of Time” which apparently sold 10 million copies.
Talking about Brian Cox and science books, this article might also be of interest: http://www.telegraph.co.uk/culture/books/7985508/Popular-science-books-take-off-a-big-bang-in-physics-publishing.html
There are quite a lot of interesting books out here (e.g. http://www.popsciencebooks.com).
I’ve pre-ordered Cox’ and Forshaw’s book – so will see if it meets the expectations!