Drunkard's Walk Forums

This is not canon at all.

Given "a continuum that has RP and London speech at either end", as John C. Wells puts it, Estuary English is right in the middle - not as posh as Received Pronunciation, not as lower-class as Cockney. It appears to be the "default" accent in London nowadays.

Why not let Minako speak English with an Estuary English accent?

Why not indeed? There are several good justifications for it, including this column at tuxedounmasked.com (which you pointed me at a couple weeks ago). Whether Minako spent only five months in England or a goodly chunk of her childhood, either way, she would get far more exposure to Estuary than RP or cockney, so it's only reasonable that's what she'd end up sounding like.

Or heaven forbid, she has a southern redneck American accent for some weird reason.