I chose not to read this with an obvious English accent. Bad accents are worse than none at all, and since my character voices tend to drift during a story anyway, I stood a better chance of maintaining them if i just concerned myself with resonance/pitch than trying to do the whole thing.
My Holmes here is a bit whiny and prissy -- I want him to sound more vibrant and excited, but still very clipped and precise. At least there's a good body of work to practice with...