How do I render time in twig without time zone interference - twig

Question

I want to grab the time only from a Drupal Date Field, and render it in a twig template separately from its date.
In my twig template for Events I currently have date listed 3 ways:
{{ content }}
displays all the fields.
And the time (sourced from a Date field) displays correctly as;
28/04/2019 - 1:11
This is the correct time as per what was entered when the content was created.
On the same page, when using:
{{ content.field_date_start }}
28/04/2019 - 1:11
is also displayed corrected.
But I want to grab the time only to display separately from the date
so I put this in the twig:
{{ node.field_date_start.value|date("g:ia") }}
which displays as:
3:11am
This is incorrect, off by 14hours (the 1.11 when entered was 1.11 pm)
How do I separate the time to a separate display within twig, but also retain the correct time as per how it was entered.
How do I enter that into a twig?
I don't want the time to change if people are entering content or viewing content in different time zones.
Example - someone creates content in Melbourne, Australia and someone else views it in London, England - the time should display the same regardless.

Answer 1

Drupal saves dates in the database as per the UTC timezone. E.g If you enter 09:00 AM as the time as a user who has a timezone of London (UTC + 1) selected in the profile, it is saved as 08:00 AM in the database. Same is true if the site's timezone is set to London (UTC +1).
I would suggest preprocessing the field and setting a variable for the start time.
function HOOK_preprocess_node(&$variables) {
$node = $variables['elements']['#node'];
$timezone = drupal_get_user_timezone();
$formatter = \Drupal::service('date.formatter');
$field_date_start = $node->get('field_date_start')->getValue()->getTimestamp();
$time = $formatter->format($field_date_start, 'custom', 'g:ia', $timezone);
$variables['start_time'] = $time;
}
And then print the value in the template as
{{ start_time }}