Iceland is on GMT/Western European Time, which is a civil timezone that would allow the implementation of a future DST.
It just happens to be +00:00 to UTC all year right now.
Iceland had DST in the 1960s.
Even more reason for someone there to be careful with timezones!
True. People I correspond with in the UK have the tendency to just say "1PM GMT" all year round, and I have to infer they're actually referring to "whatever the local time is in the UK at the moment", not specifically UTC+0 in summer.
The UK had "Double Summer Time" during WW2, and I believe again in the 1970s. Granted that was before computers but still.