Heidfeld switches back to old Williams.

Nick Heidfeld has made a desperate switch back to an old-spec Williams FW27 in an effort to resolve some of the problems encountered with the update package introduced at Magny-Cours.

The Williams team hurriedly retrieved a standard car from the test team and fitted it with the gearbox and engine that Heidfeld used on Friday. The German did not have a good first day at Silverstone, and struggled to find speed. Team sources say that the cooling problems that left Mark Webber with a burn on his hip in France have been solved, but the team still doesn't know quite where it is with the new spec car. Today will effectively be a back-to-back test between the two cars.

Heidfeld has only the two Saturday morning sessions to sort out the older package. The spare car is also still an old spec chassis, and should Heidfeld make significant progress there is a chance for Mark Webber to switch his engine to it for qualifying. However it would be a huge risk for the Aussie to do so without getting any running first.