On Friday 30 March 2018 09:08:54 D. R. Evans wrote:
> I'm not sure where to report this:
>
> I have three 24-hour TDE clocks in a panel: one on local time; one on
> London time; and one on UTC. The London and UTC clocks are reading the same
> time, but I discovered yesterday that in fact London is already on summer
> time (and has been for nearly a week, I understand), so the London time
> should be displaying a number one hour higher than UTC.
>
>   Doc

I've noticed that there is sometimes a lag for the time change. It must be 
something to do with time servers, and what gets communicated globally. I'm 
not sure if this quite answers your question, though. 

My mobile phone, for example, always changes time a week earlier than the 
actual local date for beginning and end of daylight savings time. A similar 
glitch occurs with my digital television, except that there it is always late 
to change. On the other hand, the time on my computer seems to be consistent 
and reliable; but then, I don't have a set-up like yours, where I can see the 
difference between UTC and GMT in real time. 

Bill