You have to understand History to realize how silly is your comparison of English and French diversity. NO France regional differences are NOT simple variations of a same culture. We're talking about a huge mix of celtic, germanic and latin backgrounds, which are as a matter of fact the three major cultures in the whole Western Europe.
France has been during 500 years a country which was 4 times more populated than England, a huge diversity has grown out of this. You can also see that in the diversity of French surnames. We have 4 times more family names in France than in the UK as a whole.
My history is pretty solid, being a historian and all.
England has had all the "influences" France has had, German, Roman, Celtic, Scandinavian ... much more intensely. Its biggest "foreign" influence has been you guys.I might even be tempted to say that the cores of England and France are more like each other than their peripheries ... but that would be going too far in the post-industrial age.
Diversity of "family names" depends on how names are standardized and when. Chances are your average Scottish region has generated more surnames than most of England combined, that's not got much to do with cultural diversity. France, meaning here "Gaul", has also been mostly unified in one way or another since the first century ad, though you don't need to tell me about "feudal fragmentation" or anything like that since I'm well versed in French history. Like France, England has extreme localism in peripheral locations ... Cornwall, East Anglia, East Midlands, Cumberland, Westmorland, Northumberland, Yorkshire, and so on.
Just to give a few example, people in Northern France are beer drinkers, people in Southern France are wine drinkers. As far as I know, all English people are beer drinkers.
It would depend on what English person you spoke to; in general, this splits in England according to class ... traditionally, owing to the reliance on foreign trade for that product.
Germanic influence in French regions is very far to be marginal. It's the dominant culture in Flanders and Alsace which are among the most densely populated regions in the country. But it's also very prevalent in Artois, the Ardennes, Picardy, Lorraine, Champagne and the Free county.
France lies next to the Continental Germanic continuum, naturally it is more "Germanic" in these regions ... esp. the regions most recently nabbed for the Republic. Likewise, the south and south-east of England is much more "French" than elsewhere in England. This is the nature of geography.
The strong diversity of regional cuisines in France, is also a sign of that high diversity.
All of these are part of the French gastronomy.
Not sure you are following the argument. France does have diverse regional culture ... but so does England. England has more of its population concentrated in large urban centres owing to different patterns of industrialization, which tends to make people think of the country in terms of a few large regional centres (North-West, North-East, etc). But rural England is still there, if less visible. They still prepare mutton dishes differently in Kendal than they do over the fells in Appleby! All parts of Europe have diverse cuisine ... at least traditionally, depending on produce, geography, rainfall, patterns of trade, etc. "National" and even "regional" cuisines are modern nationalistic fictions.