his girlfriend Sharon when he discovers Sharon's addiction to painkillers. Derek is beaten up by men involved with Max's secret, and Max gives him money for his honeymoon to pay them off, but Derek does not give it to them. Derek blackmails Tanya again, this time into making Joey leave Walford. At Max's stag party, it is revealed that Kat Moon (Jessie Wallace) has been having an affair with Derek. Kat goes home with him and they talk about what has just happened. Derek tells her he loves her. Kat finds a message on his phone that she left for him telling him to leave her alone. Derek says he will play it to her husband Alfie but instead he plays a message in which Kat says she wants to see Derek while Alfie is asleep. Alfie punches Derek, warning him never to return to The Queen Victoria, and hands him his wedding ring. Derek is confronted by Max who tells him that after Christmas Day, he wants nothing to do with him. Derek arrives at the Branning house for Christmas dinner as head of the family, bringing Kat with him. He is constantly undermined by Max and is shown dislike from many of those present. Kat learns that Derek played Alfie a different message, and then discovers that Derek has deleted all the messages, so she slaps him. As an act of revenge on Max, Derek calls the person involved in Max's secret, and she arrives moments before Max and Tanya are due to remarry. She introduces herself as Kirsty Branning (Kierston Wareing), Max's wife, whom he married while staying with Derek in 2011. It is revealed that Derek never handed Kirsty Max's divorce papers or the money that Max was giving to her, but allowed Max to think they were divorced, and did not tell Max about Kirsty's pregnancy, instead telling Kirsty that Max wanted the child aborted, which she did. A massive argument ensues and Derek shouts at Max and Jack, saying he has never liked Max and he was the person who locked him in a coffin as a child (Max had believed it was Jim). Derek is forced out of the house by Max, Jack and Joey, while Kat watches on. Before making one last threat, he suddenly suffers a heart attack on the street and dies. Creation and development Casting, introduction and departure On