Derry Girls will return for an extended special following the third and final season.The 45-minute episode, titled ‘The Agreement’, will return to Derry one year later as the gang prepare for their final year of school against the backdrop of the Good Friday Agreement vote.A synopsis reads: “It’s the week of the referendum on the Good Friday Agreement and its timing couldn’t be any worse as the highlight of the year, Erin and Orla’s joint 18th birthday party, threatens to be overshadowed. While the family try to get their heads around the possible outcomes of the vote, the gang realise that they may not be ready for what the future holds.”The episode will premiere the same week as the Derry Girls season three finale, which is scheduled to air on Channel 4 on May 17.Speaking about the special, show creator Lisa McGee, said: “Like all the very best 90s bands, I couldn’t resist ending our farewell tour with an encore for our loyal fans.