After Fernando Alonso's impressive victory in the British Grand Prix, there was a belief in some quarters that Ferrari had benefited from the change to the rules that was introduced for the weekend.

The four days of Silverstone were dominated by a classic Formula 1 row over a complicated technology that is difficult for the general audience to understand, but very influential on the performance of the cars.

Ferrari were very quiet through all the increasingly bitter rows over off-throttle blowing of diffusers - a technology pioneered by Red Bull with which teams gain extra downforce from blowing exhaust gases over the rear of the car even when the driver is not pressing the accelerator.

Perhaps because of Ferrari's silence, there was a widespread presumption that the effective ban on the technology for Silverstone had favoured them.

But those expecting Ferrari to fall back again from the next race in Germany, where off-throttle blowing will be allowed again, might be surprised.

There is every evidence to suggest that Ferrari's competitive leap forward was more to do with a major development they introduced on their car at Silverstone than any changes in the interpretation of the rules.

Ferrari turned up at Silverstone - the sort of high-speed, aerodynamically-demanding circuit on which its cars have resolutely refused to perform for the last few years - and showed Red Bull-matching pace, the bedrock of Alonso's victory there.

The Ferrari of the last few seasons has been strong under braking and traction - and therefore on stop/start tracks like Monaco, Montreal and Valencia.

But it has been bereft of high-speed downforce, such as was seen this season at Barcelona, where it qualified more than a second off Red Bull and, despite Alonso's starring cameo that allowed him to lead, finished a lapped fifth.

But by the time of that Barcelona race, Ferrari were already working on the upgrades that appeared at Silverstone, based on their new understanding of wind-tunnel problems that had led them into difficulties at the start of the season.

The exhaust has been re-positioned, the upper bodywork at the rear extensively re-profiled, there is a new rear wing and floor. In effect, it is a B-spec evolution of the original car.

At Silverstone, suddenly the Ferrari could get the hard Pirelli working for the first time and it no longer struggled to get the intermediate tyres quickly up to temperature.

That implies a significant boost in downforce - not that the diffuser regulations had brought everyone back to Ferrari's previous level.

The Silverstone regulations may in theory have reduced everyone's off-throttle downforce, but there was every indication that the Ferrari had more downforce than before regardless, because of the potency of its upgrade.

Unable to reach a workable off-throttle diffuser interpretation that penalised all engines and car designs equally, the governing body has agreed to revert back to the pre-Silverstone interpretation of the regulations from the next race in Germany.

This will allow back a more powerful off-throttle blowing of diffusers than was permitted at Silverstone. There is no reason to suppose that this will hurt Ferrari.

But it should help McLaren.

The MP4-26 appeared particularly ill-suited to the Silverstone regulations, as if the reduced off-throttle downforce was revealing a lot of underlying problems with the car.

It appeared as if a very delicate relationship between its various systems had been upset by a crucial change.

It was not as bad as it appeared in qualifying, the race revealing a slightly brighter picture, but it was still only a shadow of the car that had terrorised Sebastian Vettel's Red Bull in China, Barcelona, Monaco and Montreal.

There will doubtless be a lot of relief at McLaren that the full blowing of diffusers will be back from the Nurburgring.

But perhaps the biggest lesson to emerge from the events of Silverstone is that the Red Bull remains a formidable race car regardless of what is done with the off-throttle diffuser regulations.

These are no more the magic bullet of that car's performance than any of the other features claimed by rivals over the past two seasons.

The magic bullet is a tall, bald guy with a distracted look - the team's design chief, Adrian Newey.