For anyone that is having an issue with time zones and having to add events a day before/after to show them, there is a fix, although it can't be applied to the plugin - GetSimple has to be tweaked (so would need to be done again if you apply an update (e.g. 3.1) to it).
Go to admin/inc/common.php. Find all occurrences of
Replace America/New_York with your appropriate time zone.
Go to admin/inc/common.php. Find all occurrences of
Code:
$TIMEZONE = 'America/New_York'
Code:
$TIMEZONE = 'Europe/London'
-- Sam