Complex sentence: Had she lived it is likely that a spin series, with her reprising her role as Mrs. Bridges and Gordon Jackson back as Mr Hudson, would have made based in the Boarding House they had moved to at the end of "Upstairs Downstairs".
Split into simpler sentences: Had she lived it is likely that a spin series, with her reprising her role as Mrs. Bridges and Gordon Jackson back as Mr Hudson, would have made. This would have been set in the Boarding House they had moved to at the end of "Upstairs Downstairs".