[tz] Adding verified historic details

Joseph S. Myers jsm at polyomino.org.uk
Wed Sep 4 19:33:30 UTC 2013

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'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).  What we don't have is full 
details from WW1 or WW2, beyond the quote about time being put forward 
under occupation in WW2 
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).

Joseph S. Myers
jsm at polyomino.org.uk

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