The greatest concentrations are found in the West and Northwest areas of London. I live in the West of London, and can assure you that the Hounslow - Southall belt is, in fact, not much like being in England at all! It's a cultural detour that I quite enjoy, actually. Southall in particular has a massive concentration of Sikhs. I spent a few months in Southall, years back... and even the signs on the railway platform are written in Punjabi! For the most part, South/Central and Southeast are not areas where Indians usually gravitate towards; you'll find more of the Pakistani and Bangladeshi communities there, particulary in the East. Given the nuances and subtleties of Indian culture, which are markedly varied (it's a huge country, with sooo many differences), it may pay off to scope the areas mentioned, before committing to living in one. After all, no point in living where the biggest Gurdwara is, if that is not part of your lifestyle. In the end, though, and because of the varied, high concentration of 'Indians' in West London (particularly Hounslow - Southall), you may want to head there. Unfortunately, I am none too familiar with Harrow as an area; I've only ever been through it a few times, although I do recall having seen many Indians on those occasions.