Derek Warner was a criminal friend of Tom Merrick. He was first seen in the Woolpack where he berated Amos Brearly saying how Tom always said he was stuck up. In 1980, Derek and Tom stole some Christmas trees from the NY Estates plantation, running Joe Sugden over in the process. They are both caught, and Derek and Tom were both given suspended sentences. In March 1984, a few years later Derek was in trouble again for poaching. In 1986, he murdered Harry Mowlam, who was his partner in crime, and then held Donald Hinton hostage before being arrested.
1980-1981: Arrival and hit-and-run
Derek arrives in the village in early December 1980 to help friend Tom Merrick execute his plan to steal Christmas trees from Home Farm and sell them just before Christmas. The pair are caught by Joe Sugden, who tries to block their way in an attempt to stop them. However, Tom and Derek don't stop and speed off, knocking down Joe and leaving him in a ditch unconscious. Derek secretly leaves the village that night. Luckily for Joe, he is left with a sprained shoulder and a few bruises. A witness said they thought Derek and Tom were the 2 men who stole the trees. Despite fleeing the village, Derek is still caught, and arrested and charged along with Tom Merrick in January 1981.
1984-1986: Return and murder
Derek returned with Tom and Tom's daughter Sandie Merrick in March 1984. Derek convinced Tom to go poaching with him and Kevin Haynes at the Fish Farm at Home Farm, using explosives to kill the fish. In April 1984, Tom, Derek and Keith were arrested and charged with poaching.
Derek was released and returned to the village in October 1985, staging an armed robbery on a security van alongside Harry Mowlam and Keith Johnson. The robbery is witnessed by Sandie, but she is uncertain of who the criminals are, as they were wearing balaclavas, but the police are on the case. Harry takes the money for himself, and Derek holds Harry at knifepoint until Harry reveals where the money is. Derek takes action when Harry begins flashing his cash, and he and Keith take a drunken Harry to a remote country lane and rough him up, telling him to keep quiet about his riches, and to keep a low profile. This doesn't stop Harry, so Derek hunts him down. Derek beats him up after Harry has a fight with Matt Skilbeck and leaves him there unconscious by the side of the river. Harry is discovered by Henry Wilks the next day, and then dies. Matt is arrested and charged with his murder, but is proved probably innocent when evidence comes to light that Mowlam's body was found further downstream from when he fell down the bank during his fight with Matt, and Matt was not strong enough to drag him downstream. Derek still allowed Matt to take the blame. Sandie Merrick said she thought Derek was involved in the robbery.
The police investigated Derek but could not link him to the robbery as yet. A senior police officer still thinks Matt killed Mowlam. Derek starts to act strangely, and shifty, hinting how Mowlam's death was deliberate. More evidence comes to light that Derek was involved in the robbery, as well as Mowlam, when the police think the proceeds could be buried on Mowlam's land. In April, the police catch Derek and Keith digging up the stolen money, and they overhear Derek say he killed Harry Mowlam. They arrest Keith but fail to arrest Derek, so Derek runs off into the night with his shotgun. Derek holds Donald Hinton hostage in the vicarage. Thinking the police have gone, Derek takes Donald and leaves the vicarage, but he sees police outside, so fires a gunshot before frogmarching Hinton back into the vicarage. Derek is persuaded to give himself up. He then breaks down and feels guilt about letting Matt take the blame for Harry Mowlam's murder. Derek goes outside with Hinton and gives himself up. He is arrested and bundled into the police car. He later confesses to Harry's murder.
"Another pint. Amos" - First line to Amos Brearly.
"It's all I have left" - Final line to Donald Hinton, about his gun.