Thanks for the advice! It's a dystopian sci-fi set in an oppressive, chaotic near-future Britain, and centres around a group of kids in their late teens/early twenties who play a dangerous game with trains. While escaping from a rival game they witness a crime that could bring war to the country. With the government's near-uncontrollable killing machines, the Huntsmen, on their tail, they flee across the country with only their tube riding skills to protect them.
http://www.goodreads.com/author_blog_...
Chris Ward