So sorry to confuse you. Yes, it’s a pun, “maid” being ye-olde-english-speak for “girl,” and “Essex girl” being a stereotype. (I have to confess it’s not the most original slogan. It’s been on t-shirts and the like for at least a decade.)
maid in essex
I really hope it’s meant to be irony that it’s spelt ‘made/maid’ wrong….I really hope it is.