Over the past three years, there has been a slow build in awareness around the signs of coercive control.

A prominent storyline in the Archers, as well as the the case of mother-of-two Sally Challen, have both brought the issue of this subtle, persistent form of emotional and psychological abuse to the forefront.

Today, Sally Challen - who killed her husband with a hammer in 2010 - has seen her murder conviction quashed.

The Court of Appeal heard this week that the appeal may even have been partly inspired by the Archers plotline. A psychiatric assessment of Challen while she was in custody, read out by her barrister Clare Wade QC, said: "I wonder if she has been listening to this programme on Radio 4 about the woman who has been brainwashed by her husband and ends up killing him."

The significance of The Archers story, said Wade, was "that it was about coercive control."

Indeed, the radio drama followed a new law on coercive control, introduced at the end of 2015, which can carry a jail term of up to five years- raised a number of questions for people in unhappy relationships to, who might have started to wonder whether their partner’s behaviour falls under emotional abuse.

That's why we asked national domestic violence charity Women’s Aid, to explain what constitutes coercive control - and where the line falls in any relationship.