McLaren has chosen to drop its version of the blown diffuser for the remainder of the British GP weekend, though the Woking team intends to have it back on the car for the forthcoming race in Germany.

Eager not only to consolidate its lead in both championships but to score an emotional win on its home track, the Woking team is taking no chances. Therefore, in the wake of less than convincing feedback from its drivers the team will remove a number of upgraded components including the controversial blown diffuser.

"Our day was a little trickier than we'd expected," said Button, following the second practice session in which he finished thirteenth. "I couldn't get a set-up with the new package.

"We improved throughout the day," he added, "but there's still a lot of work to do, and we're not where we want to be with the balance yet."

Lewis Hamilton, who had a number of offs during the two sessions, while feeling that the team had made a step forward, admitted that it "hadn't got the optimum out of the car".

McLaren has made no secret of the fact that the Silverstone event is important to it, the team having deliberately delaying introducing the upgrade for its home race. However, even in the post-practice press conference the writing was on the wall. "As is often the case with new packages we've had to work hard to make it work today," admitted team boss Martin Whitmarsh. "As a result, the drivers haven't got really comfortable with it yet.

McLaren isn't the only team to experience teething problems with the blown diffuser which is notorious for causing overheating problems.

Having worked later into the night on Thursday, the McLaren crew had another long night last night as they changed the bodywork, floor, exhausts and heat shielding on both MP4-25s.