Chris Huhne has written to both the prime minister and deputy prime minister offering his resignation. The exchange with Cameron is in a separate post. Here are the letters between the former energy secretary and Nick Clegg, the man he once challenged for the party leadership:
Dear Nick,
I am writing to resign, with great regret, as Energy and Climate Change Secretary. I will defend myself robustly in the courts against the charges that the Crown Prosecution Service has decided to press. I have concluded that it would be distracting both to my trial defence and to my official duties if I were to continue in office as a minister.



Jim Pickard
Kiran Stacey