Yet again those dastardly Jonnie Foreigners want to slaughter my heritage. This time they’re after destroying Greenwich Mean Time.

They’re not content that our stupid government want to move us onto European time (equivalent to Summer Time) — permanently an hour adrift from real “astronomical time”. Oh no!

Now the scientific community want to abandon good old GMT completely and replace it with Coordinated Universal Time (UTC)**.

But wait! Isn’t UTC the same as GMT?

Well no, actually. Not as currently defined. Although it looks the same at the moment, the proposal appears to be to do away with leap seconds (of which there have been 24 in the last 40 years) which are inserted into UTC to help our electronic time keep track with the actual motion of the planet. Inserting leap seconds is a pain and a technical challenge, but not an insuperable challenge. But the proposal is in favour of apparent simplicity: to abandon leap seconds in favour of some currently undefined (and doubtless cocked up) solution in years to come when our modern atomic clocks have drifted too far from astronomical reality.

But surely GMT, when originally defined, did not have leap seconds defined? That’s true. Leap seconds weren’t invented until 1972, by which time GMT had been the universal time standard for almost 100 years.

So where’s the problem? Why can we not return to the original GMT, without leap seconds, if that is a scientific imperative?

Ah, now, that’s because GMT defines noon as the time the sun is exactly overhead at Greenwich. And in days of yore that was reset at regular intervals (daily?) so in effect GMT kept in track with every slight wobble in “astronomical time” automatically. But with atomic clocks that doesn’t happen. Time progresses regularly like, well, clockwork. And without leap seconds modern “electronic clock noon” (UTC) would drift away from “astronomical noon” (GMT) and that spells disaster for things like GPS.

So let’s just redefine GMT to be atomic clock time? But that would make it neither “mean time” nor “Greenwich time”, so it would be a misnomer. At least with a new name it is clear that the time being measured is different.

So … We have a working system which we are proposing to break. This is absurd. We should keep GMT (with leap seconds). It is a valuable part of our heritage. It tells people the history and science of measuring and recording time. Why are we throwing our history away so carelessly? Is nothing sacred?

** I’m sure the acronym for this should be “CUnT”.