It wasn't racist at all or anything to do with the amount of 'brownish' people. London isn't an English City, its hustle and bustle, noise and dirt. Yes, its a great tourist attraction, lovely, history, monuments, great - but its no longer an English City. Its a Metropolitan disaster and is basically a poor man's New York. They'll see you for the tourist you are and try to take your money. You'll find no hospitality and will find alot of people are rude... or just other tourists.
You want to find a city with some good pubs that know how to server beer, beer that is cold and with a bit of a head.
Manchester is OK and Birmingham is fine and has some great shops, just avoid the Pizza hut on the High Street next to Halifax - fucking awful service.