She's from Southampton which isn't posh at all, just the south of England. Accent doesn't always determine how posh you are at all. If you're from Harrogate you're probably concidered a lot more posh compared to someone from Leeds despite them being 16 miles appart and their inhabitants sharing a similar accent or at the least a Yorkshire accent which is concidered far from posh. Even myself, someone who's parents come from rural Norfolk and Manchester so very working class backgrounds has a standard British accent which sounds posh compared to my relatives just because I was born where I was.