This isn't really a Google-able thing - I've asked a couple of my friends who have been to London for references, but neither of them ever spent much time in the area I'm concerned with. I have a character who leaves a friend's flat, turns left, and after approximately twenty minutes or so, arrives in one of the seedier areas of Whitechapel (as in London, England). It's not intentional - just because he has absolutely zero knowledge of the city and is essentially wandering at random. So my question is in two parts:
1) What would be a logical place for me to put the friend's flat so that it fell about twenty minutes away from a seedy part of Whitechapel;
2) Where would a seedy part of Whitechapel be, exactly (if possible, a street name would be preferable)?