[tz] Adding verified historic details

[Lester Caine]

Joseph S. Myers wrote:
> On Wed, 4 Sep 2013, Lester Caine wrote:
>
>> Fills the picture. Europe/Isle_of_Man exists in it's own right up to 1883, and
>> then it follows Europe/London.
>
> Well - subject to confirming it did so during WW2, as you drew my
> attention to that issue.  The (UK) Emergency Powers (Defence) Act, 1939
> includes provision (subsection 4(1)(a)) for it to be extended to the Isle
> of Man by Order in Council, but I don't have a specific reference to such
> an Order in Council (presumably a UK SR&O) doing so.  (All the subsequent
> regulations then worked by modification of an Act also applying to the
> Isle of Man, so if they had the power to apply there then they would have
> done so.)

I've been slowly reading through the IOM Hansard documents but not found any 
discrepancies yet, but I have a few years to go ...

>> I'm fairly sure from the IOM documents that Jersey and Guernsey followed the
>> same date, but their archives have not got that far back yet. So do we have to
>> duplicate the whole zone record each timezone to add this one item of data?
>
> We have dates of legal adoption of GMT in Jersey (around 4pm on Saturday
> 11 June 1898) and Guernsey (18 June 1913).
Can I take those dates as facts we can add to the tz data? Is there any 
indication of the islands using a different time prior or like the main land 
they were already using 'GMT' and this just formalised it?
Typically I can't find the reference to Channel Islands again, but it was 
probably the later Summer Time changes I'm mixing up.

 > What we don't have is full
> details from WW1 or WW2, beyond the quote about time being put forward
> under occupation in WW2
> (https://en.wikipedia.org/wiki/File:Orders_of_the_German_Commandant_Evening_Post_2_July_1940.jpg
> gives one transition time as 11pm on 2 July 1940 in Jersey and we do have
> reasonably detailed information on German time from the PTB).  Certainly
> if the cut-off is 1945 or before, you need different data for them than
> for Europe/London and we don't have the full information (whereas after
> 1945, the links to Europe/London are probably correct).

I was on Jersey earlier in the year and certainly read up about that but I've 
misplaced the paper notes I made at the time :(

Paul can I use rules from another zone to fill this gap? I presume so as we have 
different rules already, but I don't think I've digested enough to know how.

-- 
Lester Caine - G8HFL
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