Originally Posted by
Christopher
Except, as noted above, in some cases, which probably wouldn't affect the OP anyway.
99.99% plus of people are not affected by this.
There is freedom of movement on the entire island of Ireland and once you clear immigration in the Republic of Ireland you are free to travel to northern Ireland. There is no ad hoc checks by UK immigration unless they have a tip off about drug smugglers or similiar. Most if not all of this was in place prior to the Good Friday Agreement.