Do I have to write with 'political allegiance' when writing for a paper?

Today, I have been doing some research on the Guardian and it's history. I know all papers have a different angle and usually come with a political opinion but do I have to have one to write for the Times, Guardian, Mail etc.. I do support I party as you will find out as I continue to blog about crap. But if I write for the Times do I have to support the right (conservatives) or Guardian, the left.
I want to know if my stories will be my own or politically spun to support political parties? Do national papers have a free voice or is journalism, just another form of PR ( this was one of my reasons for studying PR, not journalism at University.)