Ok, since it all went cold I have noticed a strange knocking noise comming from my car. It happend when I sat down on the seat or moved around on it, or went round a corner or went up or down a hill. In fact virtually anything I did made this knocking noise. I was hopeing there wasnt a problem with the suspension, but with the christmas rush on at work I had no daylight hours to myself to have a look.
Yesterday I found the problem, and why it had only started since it got cold. I could have hit myself at my stupidity.
And the reason was...
My can of de-icer was rolling around under my seat!