According to Steven Knight, season 5 will air on BBC2 in 2019. Speaking at this year's BAFTAs he confirmed the show will bow out after season 7 completes. This leaves three more seasons and possibly a movie in the pipeline.
In the House of Commons scene, both Mr. Shelby and Mr. Mosley, who are Labour MPs, appear to sitting in the opposition benches, across from the government, which was led by Labour's Ramsay McDonald at the time of Black Tuesday. Oswald Mosley held office in McDonald's government but is sitting below the gangway opposing him.
Jordan Bolger, who portrayed Isaiah in seasons 2, 3 and 4, didn't return for season 5, explaining on Twitter that 'Disappointingly it seems production aren't able to work round my other commitments'. Bolger was replaced by Daryl McCormack.