The Last Wedding was a two-part story from the original series of Mrs Brown's Boys released back in 2003.
"The Last Wedding" marks the only time Trevor and Simon are featured in the original series; both characters were written out afterwards with Paddy Houlihan and Danny O'Carroll being recast as Dermot Brown and Buster Brady respectively; Trevor is portrayed by Martin Delany in the current series whereas Simon has neither appeared nor been mentioned. Also, this is the only time that the role of Dino Doyle is portrayed by Dermot Stanley as the role was taken over in the next special, Believe It or Not by Gary Hollywood.
When Trevor is reading the letter telling him his missionary application has been accepted, some of the names visible in the letter include Paddy Houlihan (the actor playing Trevor) and Dermot O'Neill (who plays Grandad).
Grandad only appears in Part 2.