You Do Need power plug adapter while traveling from Antigua and Barbuda to Northern Ireland.

Here is Why You Need An Adapter

The outlet and plug type used in Northern Ireland is G and in Antigua and Barbuda are A and B. This is how they look like.

Antigua and Barbuda

In Antigua and Barbuda, outlets of type A and B are in use.

Type A

Type B

Northern Ireland

In Northern Ireland, outlets of type G are in use.

Type G