McLaren have reportedly decided not to run their new blown diffuser exhaust after both Lewis Hamilton and Jenson Button struggled in Friday's practices.
McLaren arrived at Silverstone with the new system but, like Ferrari and Mercedes in Valencia, they experienced difficulty in achieving a performance benefit from the so-called 'blown diffuser'.
Hamilton finished down in eighth place in Friday's practice, over 1.5s behind the leading Red Bull racer, while Button was 13th, almost two full seconds off the pace.
As such, McLaren have decided to abandon the system, at least for this weekend.
The team's engineer director Paddy Lowe told
The decision meant the team had to install their standard exhaust late on Friday night, which included changing back to the old floors in both MP4-25s.
Lowe, though, is confident McLaren can still challenge for the victory in the British GP.
"We were competitive in Turkey without the blown diffuser," he said, "and that's a similar sort of track to here.
"The blown diffuser is an influence in terms of performance around here but we've got other new parts on the car that we're very happy with so we're reasonably optimistic."
McLaren are now expected to put in more hours at the factory on the blown diffuser exhaust concept in the hope that it can be used at the German GP.