I think to suggest that dv affects only the working class is false. I personally think this is not dissimilar to 'victim blaming'. To suggest working class are more likely to be affected - it distances 'the rest of us' and makes us feel safe. And sadly myths like this are what keeps any victim from identifying abuse for what it is and why victims stay and experience repeated incidents IMHO. And domestic violence isn't seen 'in the street' in 'posh areas' because that is what it is.. violence within the home, in a domestic situation. If others see it, the perpetrator loses what he wants most - control over the situation.
Womans Aid:
Who are the victims?
The vast majority of the victims of domestic violence are women and children, and women are also considerably more likely to experience repeated and severe forms of violence, and sexual abuse. Women may experience domestic violence regardless of ethnicity, religion, class, age, sexuality, disability or lifestyle. Domestic violence can also occur in a range of relationships including heterosexual, gay, lesbian, bisexual and transgender relationships, and also within extended families.