Re: @ Vic
> I quoted your first part as it includes the bit you claim is nonsense
No it doesn't. It says the exact opposite.
You claimed that it is necessary to record UTC *and* localtime. I claim that it is only necessary to record UTC because localtime is trivially derived from it. The reverse is not true.
> UTC provides the baseline
UTC provides the *time*. Nothing to do with baselines.
> local time is derived from that and recorded accordingly to allow for time changes.
No. Localtime is derived from UTC when needed. Localtime is never stored - never. It is always derived (for display purposes - never for calculation).
> For evidential purposes you cannot derive a time after the fact
Of course you can.
Storing UTC tells you when the event happens. From there, it is a trivial amount of processing to work out what time was on someone's wristwatch at that time.
> a call record in summer time would show UTC at X and local at X + 1
Irrelevant. The local time just doesn't matter.
If you have event 1 happening at local time X, then event 2 happening one hour later, just after the end of DST, that also happens at local time X.
But if you record in UTC, event 1 happens at time Y, and event 2 happens at time Y+1 hour. The conversion to localtime is trivial.
> a suspect could argue/show they where not at the scene at the time of the call
You don't appear to understand that UTC does not have aliased timepoints in the way local times do...