The UK is not part of the Continental European Power System. For the Continental European grid, the article links to https://www.swissgrid.ch/swissgrid/en/home

The UK is not part of the Continental European Power System. For the Continental European grid, the article links to https://www.swissgrid.ch/swissgrid/en/home/experts/topics/frequency.html https://www.swissgrid.ch/swissgrid/en/home/experts/topics/fr... which states that in the case of a time drift of more than 20 seconds the frequency will be shifted to 49.990 or 50.010 to correct it.