The Tower. Pictures sent in by Globe reader Ian Fairbrother show production crew at work on the programme - featuring Game of thrones star Gemma Whelan and Hollyoaks star Emmet Scanlan. Filming took place in the next street from Seacombe ferry terminal and they where using a old merseytravel train. According to Ian, both stars where there but filming inside the train and out of sight. Gemma Whelan plays the lead role of Detective Sergeant Sarah Collins in the three-part series, adapted by Homeland writer and executive producer Patrick Harbinson. She plays the lead role of Detective Sergeant Sarah Collins.