This page links you to the ten ciphertexts that constituted the Cipher Challenge.
The competition is over and the £10,000 has now been won. Indeed, the solutions are available on-line via a paper written by the winners. However, you might still want to take up the challenge.
Stage 5 proved to be notoriously difficult.
Stage 9 requires some computer power.
Stage 10 requires lots of computer power and even more brain power.
By the way, I cannot take any responsibility if the ciphertexts on this site are not 100% identical to those published in The Code Book. Proofing ciphertexts is an enormously time consuming occupation, and I have not checked every single character. On the other hand, I have no reason to believe that the ciphertexts are not accurate.
Please note that I can no longer enter into any correspondence regarding the Cipher Challenge. It played a major role in my life for over a year, but now I have moved on to other things and do not have the time nor the memory to return it.