[kalee20]

Originally Posted by AC/HL

According to this site the average frequency for the past 24 hours was 49.98Hz
http://mainsfrequency.uk/fm-last10m

Which means, over a 24-hour day, there were 4,318,272 cycles.

There should be 4,320,000. So that's 1,628 cycles missing. This would move the seconds hand by 32.56 seconds, so, half a minute slow ties up with the observations.