And you should. Labour have just taken a hammering in both the UK and in the European Elections which you'd have thought would be a sufficiently strong message for the PM, but politicians of all varieties are notoriously bad when it comes to understanding what the electorate really think of them and their policies. You don't need to write a full and extensive letter - if you really feel Brown must go (either because you are against everything his party stands for or because you support what the Labour Party is supposed to represent and feel that if he stays in place the Labour party is in serious risk of being killed off for good) just type a few words. In fact, why not let Brown know what you think directly? Contact him - it's your right to do so. You can even copy and paste the text below...just change "signature" to your name and send it off using this link. Easy!
Dear Mr. Brown,
As a member of the British Public, I believe that it is the Prime Minister's job to represent my best interests. However, like many, I do not feel that you have thus far accomplished this task and I have no faith that you will do so in the future. With this in mind, I am asking you to step down in order to allow a contest to decide the Labour Party's leadership. We, the British People, did not vote you into power and this is the only way that we can make our opinion plain to you.