A week after buying a Mondeo Ghia 2L TDCi (140) (57 plate) the car developed a really annoying squeak that seemed to be coming from the interior somewhere, and only when the car was being driven. I finally tied it down to the door seals on both the near side doors. It appears to be caused by the rubber seals on the doors rubbing against the seals on the door surrounds on the body of the car - possibly due to polish being applied during the pre-handover valet. The simple solution is to rub into all the seals a cream compound called Einsett Gummi Pfege - available on E-Bay. The primary function of the compound is to revitalise rubber seals and prevent the rubber seals from sticking in the event of a hard frost but is also cures the squeaking problem. I hope this will help others with the same problem.