I don't want (and I'm not qualified) to get into heavy subjects but England is a very complex place and just about everything in it's history and make-up works against its folk traditions.

Here is a brief(ish) list;
(a) extreme social class distinctions (even up to recently)
Royalty, Ruling Class, Upper Class, Upper Middle Class, Middle Class, Servant and Lower Class. The vast majority of the population was Lower Class, where the real folk tradition lived. But their tradition was not "cool" it was quaint at best. Everybody wanted to leave behind their existing class and "better" themselves so a certain stigma was attached to the "goings on" of the lower orders. Folk music=lower class music.

(b) many diverse cultures (French, Cornish, Saxon etc.)
Since the Norman invasions in the 11th c., "English" people, ie., South East England, are really emigrant French. Most of the "real" English were forced North and west into Wales, Cornwall, etc.

(c) worldwide imperial colonisation
This brought about even more diverse cultural pressure on "the tradition" as it freely mixed and mingled with what was already fragmented.

(d) rapid transitions to urbanisation and mechanisation
For a number of centuries the famed English countryside settled down into a stable pattern allowing a tradition to emerge with natural regional variation but with each area sharing portions of the total set. But rapid industrialization, starting in the last century and continuing into the 1960's, decimated the rural populations. There is now no real rural working class so there is no "living" rural folk tradition except for parts of Cornwall etc. "Quaint" Folk Clubs are the keepers of the tradition now.
Those who moved to the urban areas eventually succumbed to the cosmopolitan influences of the towns.
But urban traditions grew such as the Cockney traditions etc. Some of older rural traditions survived in a modified but recognizable form due to the proximity of the rural areas and the strength of the regional tradition, eg. Geordie.

(e) rapid decline in imperial power and collapse of empire
Two world wars and the collapse of the Empire in a span of only 50 years brought massive changes to the land called England. The Middle Class swelled, large influxes of immigrants came from former colonies, rural depopulisation accelerated, "old" industries (mining, textiles, shipbuilding) went into decline and the class structure started to collapse. There wasn't much time for tradition really with so much happening even the urban working class traditions went into freefall.

(f) dismemberment process of Britain via devolution
Britain is now slowly drawing in on itself with devolved governments in Scotland and Wales. "British" culture was always seen as "English" culture and by default Welsh choirs and Scottish bagpipes were "British" and therefore "English". But what of Morris dancers? Yes, this is English.

But English folk traditions have endured so much competition and pressure for so long that it needs time to re-emerge. English people are confused about what is their tradition not to mind what their folk music is. How do you define "being English", for that matter? Just because you were born in London does that make you English – even though your mother is Irish and your father is Jamaican? What is your tradition? Do you see Morris dancing as your tradition? Or rather, how can you see Morris dancing as your tradition?

Martin Carthy and a few others have given England breathing space and have kept a proud and excellent tradition alive. The wealth and organization of the old Empire has much of England's tradition safely archived. Given time and nurturing, English folk music will stand proud again on an equal footing with other folk music cultures. And of course the new branches of the tradition will continue to develop with the multitude of ethnic flavours and influences.

Now that I have offended thousands of people who misunderstand my argument I shall slip away quietly to bed. I have written far too much and far too little such that I have tried to cover as much ground as possible but have had to generalise to the extreme. No, I haven't mentioned English sea shanties etc., etc. Where do I draw the line?

Go on, all the ammunition is there, tear me to shreads.

Goodnight all.

Frank