No. 2 is the IRRS 50th Anniversary special to Derry. Not sure of exact date, but definitely not 1980 as loco and train in post-1987 IR livery.
No. 4 is the PWI Convention special at Portrush. Not sure if it was the actual special which ran from Portrush to Dublin (being attached to the 09:00 ex-Belfast at Lisburn, or the trial train to clear MkIII stock to Portrush sometime earlier.
No. 4 is Macmine Junction. Grey 121 on the other side of the platform, presumably on a North Wexford service.