The Empire, and moreso the Sith, have always been pro-human (as far as lore is concerned). It doesn't matter what planet you come from, as long as you're genetically human, you jump to the front of the line. An "alien," to the Sith, is anyone that isn't completely genetically human. It was especially so during Palpatine's reign, as he hated any and all non-humans (though he tolerated some, i.e. Maul and Thrawn, mainly for their usefulness).
Accents are a little shakier, as lore-wise a British accent is considered a "Coruscanti" accent. However, since we are 3500 years prior to Coruscant becoming Imperial Center (when said accent becomes widely known), I suppose it works as sort of an origin bit.