The map is actually a reasonably accurate reflection of where the largest communities of Asian British and South Asian immigrants live.

That said, whether it's disproportionately common amongst Indian ethnic groups or otherwise, you won't meet that many Patels even in the relevant parts of London. To put things into perspective, the population of Greater London is ~7 million, and there are <100,000 Patels in the entire UK sources: http://gbnames.publicprofiler.org/Statistics.aspx?name=PATEL... http://www.telegraph.co.uk/news/uknews/5040755/Britains-most...

If you want a better picture of the relative sizes of UK ethnic groups by district (amongst many other demographic factors) then the interactive map at www.censusprofiler.org is awesome.

Informally, that seems to be true. See Patel: http://en.wikipedia.org/wiki/Patel

A time based view would be interesting.

The next generation moves away form these ghettos and assimilates into the rest of London, after a few generations there are only hotspots of the original immigrants left in these places and then usually only if there are strong religous reasons.

If you go into London through the east end (Brick lane etc) the names of pubs are Huguenot (from early 1800s) then there are names of Jewish merchants and tailors on the top floors of buildings (from the early 1900s) then the ground floor is now Bangladeshi.

Difficult to draw too many conclusions from that since whilst Jones and Williams are more common in Wales, the vast majority of British people with those surnames are English. Jones and Williams are the second and third most popular names in most of the outer suburbs too. If there's any pattern here it's more likely to be the reverse; the density of very English Smiths is much greater in the outer suburbs.

The nationalistic Welsh will tell you they are the real british people, but displaced and pushed westwards (into what is now Wales) by the Romans, Normans, Anglo Saxons etc. So a name might be mostly Welsh now, but the people with that name might have lived in that area for a very long time,

In the 15thC a Welshman took the throne of England (Henry VII) and brought a lot of fellow countrymen into court with him, so they needn't have been poorer immigrants

Welsh predates english by centuries, in terms of lineage. Most of europe once spoke celtic languages that are most closely connected to welsh.

I'd guess it's because the welsh has a head start on migration of a few hundred years over the other groups on the chart.

The boundaries in the map are borough boundaries.

I found it interesting that a couple of zoom levels down, you can see a big cluster of Irish names on the Brent side of the Kilburn High Road, and another in W7.