It's called the UK Sport bike, designed by a Greek guy who's name I forget. It was funded in part by the British government throught the World Class Performance Plan, and is only available to riders on the British team (grrr, I want one). There are three seat tube sizes, two rear end sizes and long and short top tubes, so quite a wide range of sizes available (I think). They also make their own forks, bars and disk wheels, it makes for quite an impressive package. My personal favourite track bike around (also available in a road version with titanium dropouts, perfect for winning the World TT championship).